C语言数组的概念
来源：互联网 发布：上海知柚网络科技公司 编辑：程序博客网 时间：2024/05/16 04:34
1.C语言数组的概念
在《printf函数的高级用法》一节中我们举了一个例子，是输出一个 4×4 的整数矩阵，代码如下：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a1<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a2<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">345</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a3<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">700</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a4<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">22</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> b1<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">56720</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b2<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">9999</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b3<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">20098</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b4<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> c1<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">233</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c2<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">205</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c3<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c4<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">6666</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> d1<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d2<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d3<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">23</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d4<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">23006783</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a2<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a3<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a4<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b2<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b3<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b4<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c2<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c3<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c4<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d2<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d3<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d4<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>20 345 700 2256720 9999 20098 2233 205 1 666634 0 23 23006783矩阵共有 16 个整数，我们为每个整数定义了一个变量，也就是 16 个变量。那么，为了减少变量的数量，让开发更有效率，能不能为多个数据定义一个变量呢？比如，把每一行的整数放在一个变量里面，或者把 16 个整数全部都放在一个变量里面。
我们知道，要想把数据放入内存，必须先要分配内存空间。放入4个整数，就得分配4个
int类型的内存空间：int a[4];这样，就在内存中分配了4个
int类型的内存空间，共 4×4=16 个字节，并为它们起了一个名字，叫a。我们把这样的一组数据的集合称为数组（Array），它所包含的每一个数据叫做数组元素（Element），所包含的数据的个数称为数组长度（Length），例如
int a[4];就定义了一个长度为4的整型数组，名字是a。数组中的每个元素都有一个序号，这个序号从0开始，而不是从我们熟悉的1开始，称为下标（Index）。使用数组元素时，指明下标即可，形式为：
arrayName[index]arrayName 为数组名称，index 为下标。例如，a[0] 表示第0个元素，a[3] 表示第3个元素。
接下来我们就把第一行的4个整数放入数组：
a[0]=20;a[1]=345;a[2]=700;a[3]=22;这里的0、1、2、3就是数组下标，a[0]、a[1]、a[2]、a[3] 就是数组元素。
我们来总结一下数组的定义方式：
dataType arrayName[length];dataType 为数据类型，arrayName 为数组名称，length 为数组长度。例如：
float m[12];char ch[9];
注意：
1) 数组中每个元素的数据类型必须相同，对于
int a[4];，每个元素都必须为 int。2) 数组下标必须是整数，取值范围为 0 ≤ index < length。
3) 数组是一个整体，它的内存是连续的，下面是
int a[4];的内存示意图：
数组的初始化
上面的代码是先定义数组再给数组赋值，我们也可以在定义数组的同时赋值：int a[4] = {20, 345, 700, 22};{ }中的值即为各元素的初值，各值之间用,间隔。对数组赋初值需要注意以下几点：
1) 可以只给部分元素赋初值。当
{ }中值的个数少于元素个数时，只给前面部分元素赋值。例如：int a[10]={12, 19, 22 , 993, 344};表示只给 a[0]~a[4] 5个元素赋值，而后面5个元素自动赋0值。当赋值的元素少于数组总体元素的时候，剩余的元素自动初始化为 0：对于short、int、long，就是整数0；对于char，就是字符 '\0'；对于float、double，就是小数0.0。
我们可以通过下面的形式将数组的所有元素初始化为 0：
int a[10] = {0};char c[10] = {0};float f[10] = {0};由于剩余的元素会自动初始化为0，所以只需要给第0个元素赋0值即可。示例：输出数组元素。
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">299</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">92</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//从控制台输入数据为每个元素赋值</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//输出数组元素</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">putchar</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">'</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">putchar</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">'</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> </li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>90 100 33 22 568 10299 34 92 100 0 090 100 33 22 568 10
2) 只能给元素逐个赋值，不能给数组整体赋值。例如给十个元素全部赋1值，只能写为：
int a[10]={1, 1, 1, 1, 1, 1, 1, 1, 1, 1};而不能写为：int a[10]=1;
3) 如给全部元素赋值，那么在数组定义时可以不给出数组的长度。例如：
int a[]={1,2,3,4,5};等价于int a[5]={1,2,3,4,5};最后，我们借助数组来输出一个 4×4 的矩阵：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">4</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">345</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">700</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">22</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">4</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">56720</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">9999</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">20098</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">4</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">233</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">205</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">6666</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">4</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">23</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">23006783</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%-9d %-9d %-9d %-9d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>上节讲解的数组可以看作是一行连续的数据，只有一个下标，称为一维数组。在实际问题中有很多量是二维的或多维的，因此C语言允许构造多维数组。多维数组元素有多个下标，以确定它在数组中的位置。本节只介绍二维数组，多维数组可由二维数组类推而得到。
二维数组的定义
二维数组定义的一般形式是：dataType arrayName[length1][length2];其中，dataType 为数据类型，arrayName 为数组名，length1 为第一维下标的长度，length2 为第二维下标的长度。例如：
int a[3][4];定义了一个3行4列的数组，共有3×4=12个元素，数组名为a，即：
a[0][0], a[0][1], a[0][2], a[0][3]
a[1][0], a[1][1], a[1][2], a[1][3]
a[2][0], a[2][1], a[2][2], a[2][3]
在二维数组中，要定位一个元素，必须给出一维下标和二维下标，就像在一个平面中确定一个点，要知道x坐标和y坐标。例如，a[3][4] 表示a数组第3行第4列的元素。
二维数组在概念上是二维的，但在内存中地址是连续的，也就是说存储器单元是按一维线性排列的。那么，如何在一维存储器中存放二维数组呢？有两种方式：一种是按行排列， 即放完一行之后顺次放入第二行。另一种是按列排列， 即放完一列之后再顺次放入第二列。
在C语言中，二维数组是按行排列的。也就是先存放a[0]行，再存放a[1]行，最后存放a[2]行；每行中的四个元素也是依次存放。数组a为int类型，每个元素占用4个字节，整个数组共占用4×(3×4)=48个字节。
【示例】一个学习小组有5个人，每个人有三门课的考试成绩。求全组分科的平均成绩和各科总平均成绩。
--张王李赵周Math8061598576C7565638777English9271709085
可设一个二维数组a[5][3]存放五个人三门课的成绩。再设一个一维数组v[3]存放所求得各分科平均成绩，设变量average 为全组各科总平均成绩。编程如下：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//二维数组下标</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//当前科目的总成绩</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> average<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//总平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//各科平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//用来保存每个同学各科成绩的二维数组</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input score:</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>j<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>j<span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//输入每个同学的各科成绩</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">+=</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>j<span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//计算当前科目的总成绩</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]=</span>sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">/</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">// 当前科目的平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> average <span class="sh_symbol" style="color: rgb(48, 48, 238);">=(</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]+</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]+</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">])/</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Math: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">C Languag: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">English: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Total:%d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> average<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input score:
80 61 59 85 76 75 65 63 87 77 92 71 70 90 85↙
Math: 72
C Languag: 73
English: 81
Total:75
程序中首先用了一个双重循环。在内循环中依次读入某一门课程的各个学生的成绩，并把这些成绩累加起来，退出内循环后再把该累加成绩除以5送入v[i]之中，这就是该门课程的平均成绩。外循环共循环三次，分别求出三门课各自的平均成绩并存放在v数组之中。退出外循环之后，把v[0]、v[1]、v[2]相加除以3即得到各科总平均成绩。最后按题意输出各个成绩。
二维数组的初始化
二维数组的初始化可以按行分段赋值，也可按行连续赋值。例如对数组a[5][3]，按行分段赋值可写为：
int a[5][3]={ {80,75,92}, {61,65,71}, {59,63,70}, {85,87,90}, {76,77,85} };按行连续赋值可写为：int a[5][3]={80, 75, 92, 61, 65, 71, 59, 63, 70, 85, 87, 90, 76, 77, 85};这两种赋初值的结果是完全相同的。【示例】求各科平均分和总成绩平均分。
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//二维数组下标</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//当前科目的总成绩</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> average<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//总平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//各科平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]=</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">80</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">75</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">92</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">61</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">65</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">71</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">59</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">63</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">70</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">85</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">87</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">90</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">76</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">77</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_number" style="color: rgb(50, 186, 6);">85</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>j<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> j<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">+=</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>j<span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//计算当前科目的总成绩</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]=</span>sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">/</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">// 当前科目的平均分</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> sum<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> average <span class="sh_symbol" style="color: rgb(48, 48, 238);">=(</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]+</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]+</span>v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">])/</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Math: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">C Languag: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">English: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> v<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Total:%d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> average<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Math: 72
C Languag: 73
English: 81
Total:75
对于二维数组初始化赋值还有以下说明
1) 可以只对部分元素赋初值，未赋初值的元素自动取0值。例如：int a[3][3]={{1},{2},{3}};是对每一行的第一列元素赋值，未赋值的元素取0值。 赋值后各元素的值为：1 0 0
2 0 0
3 0 0
int a [3][3]={{0,1},{0,0,2},{3}};赋值后的元素值为：0 1 0
0 0 2
3 0 0
2) 如对全部元素赋初值，则第一维的长度可以不给出。例如：
int a[3][3]={1,2,3,4,5,6,7,8,9};可以写为：int a[][3]={1,2,3,4,5,6,7,8,9};3) 数组是一种构造类型的数据。二维数组可以看作是由一维数组的嵌套而构成的。设一维数组的每个元素都又是一个数组，就组成了二维数组。当然，前提是各元素类型必须相同。根据这样的分析，一个二维数组也可以分解为多个一维数组。C语言允许这种分解。
如二维数组a[3][4]，可分解为三个一维数组，其数组名分别为：a[0]、a[1]、a[2]。
对这三个一维数组不需另作说明即可使用。这三个一维数组都有4个元素，例如：一维数组a[0]的元素为a[0][0], a[0][1], a[0][2], a[0][3]。必须强调的是，a[0], a[1], a[2]不能当作下标变量使用，它们是数组名，不是一个单纯的下标变量。
3.C语言数组元素的查询
在实际开发中，经常需要查询数组中的元素。例如，学校为每位同学分配了一个唯一的编号，现在有一个数组，保存了实验班所有同学的编号信息，如果有家长想知道他的孩子是否进入了实验班，只要提供孩子的编号就可以，如果编号和数组中的某个元素相等，就进入了实验班，否则就没进入。
不幸的是，C语言标准库没有提供与数组查询相关的函数，所以我们只能自己编写代码。
对无序数组的查询
所谓无序数组，就是数组元素的排列没有规律。无序数组元素查询的思路也很简单，就是用循环遍历数组中的每个元素，把要查询的值挨个比较一遍。请看下面的代码：<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> nums<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">296</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">177</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">23</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">999</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> subscript <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">-</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Please input an integer: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>num<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>nums<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">==</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> subscript <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">break</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>subscript<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d isn't in the array.</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">else</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d is in the array, and it's subscript is %d.</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> subscript<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Please input an integer: 100
100 is in the array, and it's subscript is 7.
Please input an integer: 28
28 isn't in the array.
第10~15行代码是关键，它会遍历数组中的每个元素，和用户输入的数字进行比较，如果相等就获取它的下标并跳出循环。
注意：数组下标的取值范围是非负数，当 subscript >= 0 时，该数字在数组中，当 subscript < 0 时，该数字不在数组中，所以在定义 subscript 变量时，必须将其初始化为一个负数。
对有序数组的查询
查询无序数组需要遍历数组中的所有元素，而查询有序数组只需要遍历其中一部分元素。例如有一个长度为10的整型数组，它所包含的元素按照从小到大的顺序（升序）排列，假设比较到第4个元素时发现它的值大于输入的数字，那么剩下的5个元素就没必要再比较了，肯定也大于输入的数字，这样就减少了循环的次数，提高了执行效率。请看下面的代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> nums<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">6</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">23</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">177</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">296</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">999</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> subscript <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">-</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Please input an integer: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>num<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>nums<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">>=</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>nums<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">==</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> subscript <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">break</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>subscript<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d isn't in the array.</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">else</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d is in the array, and it's subscript is %d.</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> num<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> subscript<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>- 如果 nums[i] == num，则 num 在数组中，那么就需要给 subscript 赋值，记录当前元素的下标；
- 如果 nums[i] > num，则 nums 不在数组中。
无论哪种情况，都没有必要再继续循环下去了，所以一旦满足 nums[i] >= num，就应该使用 break 跳出循环。
4.C语言字符数组和字符串
用来存放字符的数组称为字符数组，例如：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//一维字符数组</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">][</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//二维字符数组</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]=</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_string" style="color: rgb(24, 97, 167);">'c'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">' '</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'p'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'r'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'o'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'g'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'r'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'a'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span><span class="sh_string" style="color: rgb(24, 97, 167);">'m'</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">// 给部分数组元素赋值</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]=</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_string" style="color: rgb(24, 97, 167);">'c'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">' '</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'p'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'r'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'o'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'g'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'r'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'a'</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">'m'</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//对全体元素赋值时可以省去长度</span></li></ol>C语言规定，可以将字符串直接赋值给字符数组，例如：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_string" style="color: rgb(24, 97, 167);">"c.biancheng.net"</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//这种形式更加简洁，实际开发中常用</span></li></ol><ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_string" style="color: rgb(24, 97, 167);">"c.biancheng.net"</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//这种形式更加简洁，实际开发中常用</span></li></ol>在C语言中，字符串总是以
'\0'作为串的结束符。上面的两个字符串，编译器已经在末尾自动添加了'\0'。puts 和 printf 在输出字符串时会逐个扫描字符，直到遇见 '\0' 才结束输出。请看下面的例子：'\0'是ASCII码表中的第0个字符，用NUL表示，称为空字符。该字符既不能显示，也不是控制字符，输出该字符不会有任何效果，它在C语言中仅作为字符串的结束标志。
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"C Language"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str3<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"You are a good</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\0</span><span class="sh_string" style="color: rgb(24, 97, 167);"> boy!"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str1: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str2: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str3: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str3<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>str1: http://c.biancheng.net
str2: C Language
str3: You are a good
str1 和 str2 很好理解，编译器会在字符串最后自动添加 '\0'，并且数组足够大，所以会输出整个字符串。对于 str3，由于字符串中间存在 '\0'，printf() 扫描到这里就认为字符串结束了，所以不会输出后面的内容。
需要注意的是，用字符串给字符数组赋值时由于要添加结束符 '\0'，数组的长度要比字符串的长度（字符串长度不包括 '\0'）大1。例如：
char str[] = "C program";该数组在内存中的实际存放情况为：
字符串长度为 9，数组长度为 10。
5.C语言字符串处理函数
C语言提供了丰富的字符串处理函数，例如字符串的输入、输出、合并、修改、比较、转换、复制、搜索等，使用这些现成的函数可大大减轻编程的负担。
用于输入输出的字符串函数，例如printf、puts、scanf、gets等，使用时应包含头文件stdio.h，使用其它字符串函数则应包含头文件string.h。
字符串长度函数strlen
strlen 是 string length 的缩写，用来获得字符串的长度。所谓长度，就是包含多少个字符（不包括字符串结束标志 '\0'）。语法格式为：strlen(arrayName);strlen 将返回字符串的长度，它是一个整数。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><string.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]=</span><span class="sh_string" style="color: rgb(24, 97, 167);">"C language"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> len <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_function" style="color: rgb(209, 28, 237);">strlen</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"The lenth of the string is %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> len<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>The lenth of the string is 10
需要说明的是，strlen 会从字符串的第 0 个字符开始计算，直到遇到字符串结束标志 '\0'。将上面代码中的 str 改为：
char str[]="C \0language";那么输出结果就是：
The lenth of the string is 2
字符串连接函数 strcat
strcat 是 string catenate 的缩写，意思是把两个字符串拼接在一起，语法格式为：strcat(arrayName1, arrayName2);arrayName1、arrayName2 为需要拼接的字符串。
strcat 将把 arrayName2 连接到 arrayName1 后面，并删去 arrayName1 最后的结束标志 '\0'。这就意味着，arrayName1 的长度要足够，必须能够同时容纳 arrayName1 和 arrayName2，否则会越界。
strcat 返回值为 arrayName1 的首地址。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><string.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">40</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]=</span><span class="sh_string" style="color: rgb(24, 97, 167);">"My name is "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input your name:"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">gets</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">strcat</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span>str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input your name:xiao p
My name is xiao p
字符串复制函数strcpy
strcpy 是 string copy 的缩写，意思是字符串复制，语法格式为：strcpy(arrayName1, arrayName2);strcpy 会把 arrayName2 中的字符串拷贝到 arrayName1 中，串结束标志 '\0' 也一同拷贝。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><string.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">15</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]=</span><span class="sh_string" style="color: rgb(24, 97, 167);">"C Language"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">strcpy</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>C Language
strcat 要求 arrayName1 要有足够的长度，否则不能全部装入所拷贝的字符串。
字符串比较函数strcmp
strcmp 是 string compare 的缩写，意思是字符串比较，语法格式为：strcmp(arrayName1, arrayName2);arrayName1 和 arrayName2 是需要比较的两个字符串。
字符本身没有大小之分，strcmp() 是以各个字符在ASCII 码表上对应的数值进行比较的。strcmp() 首先将 arrayName1 中第0个字符的 ASCII 码值减去 arrayName2 中第0个字符的 ASCII 码值，若差值为 0，则说明两个字符相同，再继续比较下个字符，若差值不为 0 则将差值返回。例如字符串"Ac"和"ba"比较则会返回字符"A"(65)和'b'(98)的差值(－33)。
返回值：若 arrayName1 和 arrayName2 相同，则返回0；若 arrayName1 大于 arrayName2，则返回大于 0 的值；若 arrayName1 小于 arrayName2，则返回小于0 的值。
【示例】对4组字符串进行比较。
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><string.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">*</span>a <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"aBcDeF"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">*</span>b <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"AbCdEf"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">*</span>c <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"aacdef"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">*</span>d <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"aBcDeF"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"strcmp(a, b) : %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_function" style="color: rgb(209, 28, 237);">strcmp</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">));</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"strcmp(a, c) : %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_function" style="color: rgb(209, 28, 237);">strcmp</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">));</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"strcmp(a, d) : %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_function" style="color: rgb(209, 28, 237);">strcmp</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> d<span class="sh_symbol" style="color: rgb(48, 48, 238);">));</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>strcmp(a, b) : 32
strcmp(a, c) :-31
strcmp(a, d) : 0
6.C语言字符串的输入输出
字符串的输出
在C语言中，输出字符串的函数有两个：- puts()：直接输出字符串，并且只能输出字符串。
- printf()：通过格式控制符 %s 输出字符串。除了字符串，printf() 还能输出其他类型的数据。
这两个函数前面已经讲过了，这里不妨再演示一下，请看下面的代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//通过变量输出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//直接输出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//通过变量输出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//直接输出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>http://c.biancheng.net
http://c.biancheng.net
http://c.biancheng.net
http://c.biancheng.net
在 printf() 函数中使用
%s输出字符串时，在变量列表中给出数组名即可，不能写为printf("%s", str[]);。字符串的输入
在C语言中，输入字符串的函数有两个：- scanf()：通过格式控制符 %s 输入字符串。除了字符串，scanf() 还能输入其他类型的数据。
- gets()：直接输入字符串，并且只能输入字符串。
1) 使用 scanf() 读取字符串
请先看下面的例子：<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input str1: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input str2: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str1: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">str2: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input str1: c.biancheng.net↙
Input str2: Java Python C-Sharp↙
str1: c.biancheng.net
str2: Java
由于字符数组长度为30，因此输入的字符串长度必须小于30，以留出一个字节用于存放字符串结束标志`\0`。
对程序的说明：
① 我们本来希望将 "Java Python C-Sharp" 赋值给 str2，但是 scanf() 只读取到 "Java"，这是因为 scanf() 读取到空格时就认为字符串输入结束了，不会继续读取了。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> str3<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input string: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%s"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str3<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str1: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">str2: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">str3: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str3<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input string: Java Python C-Sharp↙
str1: Java
str2: Python
str3: C-Sharp
第一个 scanf() 读取到 "Java" 后遇到空格，结束读取，将"Python C-Sharp" 留在缓冲区。第二个 scanf() 直接从缓冲区中读取，不会等待用户输入，读取到 "Python" 后遇到空格，结束读取，将 "C-Sharp" 留在缓冲区。第三个 scanf() 读取缓冲区中剩下的内容。
② 在《从键盘输入数据》中讲到，scanf 的各个变量前面要加取地址符
&，用以获得变量的地址，例如：int a, b;scanf("%d %d", &a, &b);但是在本节的示例中，将字符串读入字符数组却没有使用&，例如：char str1[20], str2[20], str3[20], str4[20];scanf("%s %s %s %s",str1, str2, str3, str4);这是因为C语言规定，数组名就代表了该数组的地址。整个数组是一块连续的内存单元，如有字符数组char c[10]，在内存可表示为：
C语言还规定，数组名所代表的地址为第0个元素的地址，例如
char c[10];，c就代表c[0]的地址。第0个元素的地址就是数组的起始地址，称为首地址。也就是说，数组名表示数组的首地址。设数组c的首地址为0X2000，也即c[0]地址为0X2000，则数组名c就代表这个地址。因为c已经表示地址，所以在c前面不能再加取地址符&，例如写作
scanf("%s",&c);是错误的。有了首地址，有了字符串结束符'\0'，就可以在内存中完整定位一个字符串了。例如：
printf("%s", c);printf 函数会根据数组名找到c的首地址，然后逐个输出数组中各个字符直到遇到 '\0' 为止。int、float、char 类型的变量表示数据本身，数据就保存在变量中；而数组名表示的是数组的首地址，数组保存在其他内存单元，数组名保存的是这块内存的首地址。后面我们会讲解指针，大家将会有更加深刻的理解。
2) 使用 gets() 读取字符串
gets 是 get string 的缩写，意思是获取用户从键盘输入的字符串，语法格式为：gets(arrayName);arrayName 为字符数组。从键盘获得的字符串，将保存在 arrayName 中。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input str1: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">gets</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input str2: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">gets</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"str1: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">str2: %s</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input str1: Java Python C-Sharp↙
Input str2: http://c.biancheng.net↙
str1: Java Python C-Sharp
str2: http://c.biancheng.net
可以发现，当输入的字符串中含有空格时，输出仍为全部字符串，这说明 gets() 函数不会把空格作为输入结束的标志，而只把回车换行作为输入结束的标志，这与 scanf() 函数是不同的。
总结：如果希望读取的字符串中不包含空格，那么使用 scanf() 函数；如果希望获取整行字符串，那么使用 gets() 函数，它能避免空格的截断。
7.C语言数组的静态行、越界以及溢出
在C语言中，数组一旦被定义后，占用的内存空间就是固定的，不能在任何位置插入元素，也不能在任何位置删除元素（当然可以修改元素），我们将这样的数组称为静态数组（Static Array）。
数组越界
C语言数组不会自动扩容，当下标小于零或大于等于数组长度时，就发生了越界（Out Of Bounds），访问到数组以外的内存。如果下标小于零，就会发生下限越界（Off Normal Lower）；如果下标大于等于数组长度，就会发生上限越界（Off Normal Upper）。C语言为了提高效率，并不会对越界行为进行检查，即使越界了，也能够正常编译，只有在运行期间才可能会发生问题。请看下面的代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=-</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><=</span><span class="sh_number" style="color: rgb(50, 186, 6);">4</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"a[%d]=%d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>a[-2]=-858993460
a[-1]=-858993460
a[0]=10
a[1]=20
a[2]=30
a[3]=-858993460
a[4]=-858993460
越界访问的数组元素都是垃圾值，没有实际的含义，因为数组之外的内存我们并不知道是什么，可能是其他变量的值，可能是附加数据，可能是一个地址，这些都是不可控的。
由于C语言的”放任“，我们访问数组时必须非常小心，要确保不会发生越界。
当发生数组越界时，如果我们对该内存有访问权限，程序将正常运行，但会出现不可控的结果（如上例所示）；如果没有访问权限，程序将会崩溃。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10000</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>
在VS2010下运行，会出现运行时错误：
每个程序可访问的内存都是有限的，该程序要访问 4*10000 字节处的内存，显然太远了，超出了程序的访问范围。这个地方的内存可能是其他程序的内存，可能是系统本身占用的内存，可能是没被使用的内存，如果放任这种行为，将带来非常危险的后果，操作系统只能让程序停止运行。
数组溢出
当赋予数组的元素个数超过数组长度时，就会发生溢出（Overflow）。如下所示：int a[3] = {1, 2, 3, 4, 5};数组长度为3，初始化时却赋予5个元素，超出了数组容量，所以只能保存前3个元素，后面的元素被丢弃。VC/VS 发现数组溢出会报错，禁止编译通过；而GCC不会，它只给出警告。
一般情况下数组溢出不会有什么问题，顶多是丢弃多余的元素。但对于字符数组，有时会产生不可控的情况，请看下面的代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">system</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"pause"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>
字符串的长度大于数组长度，数组只能容纳字符串的前面一部分，也就是 "http://c.b"，即使编译器在最后添加了 '\0'，它也保存不到数组里面，所以 printf() 扫描数组时不会遇到结束符 '\0'，只能继续向后扫描。而后面内存中的数据我们不知道是什么，字符能否识别，何时遇到 '\0'，这些都是不确定的。当字符无法识别时，就会出现乱码，显示奇怪的字符。
由此可见，在用字符串给字符数组赋值时，要保证数组长度大于字符串长度，以容纳结束符 '\0'。
8.C语言变长数组
目前使用的C语言有两个版本，C89和C99。C89（也称ANSI C）是较早的版本，也是最经典的版本，国内大学几乎都是以该版本为基础进行授课。C99是后来对C89的升级，增添了一些内容，语法更加灵活，同时兼容C89。关于C语言标准的更多内容请访问：C语言的发展及其版本
各种编译器都遵循C89标准，但对C99的支持却不同：开源组织的GCC已经支持了大部分的C99标准，而微软的VC、VS对C99却不感兴趣（后来的VS2013、VS2015才慢慢支持）。
为什么要讨论这个问题呢？因为C89和C99对数组做出了不同的规定：在C89中，必须使用数值常量指明数组长度，不能使用变量（不管变量有没有被初始化）；而在C99中，可以使用变量指明数组长度。
下面的代码使用数值常量指明数组长度，在任何编译器下都能编译通过：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//长度为10</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">*</span><span class="sh_number" style="color: rgb(50, 186, 6);">5</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//长度为15</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> c<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">4+8</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//长度为12</span></li></ol>
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> m <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> n<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>n<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>m<span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>n<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li></ol>
在实际编程中，有时数组的长度不能提前确定，如果这个变化范围小，那么使用数值常量定义一个足够大的数组就可以，如果这个变化范围大，就可能会浪费空间，这时就可以使用变长数组。请看下面的代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> n<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input string length: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>n<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">fflush</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>stdin<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>n<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Input string: "</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">gets</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">puts</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>str<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Input string length: 30↙
Input string: http://c.biancheng.net↙
http://c.biancheng.net
9.对C语言数组的总结以及实例讲解
数组（Array）是一系列相同类型的数据的集合，可以是一维的、二维的、多维的；最常用的是一维数组和二维数组，多维数组较少用到。
对数组的总结
1) 数组的定义格式为：type arrayName[length]type 为数据类型，arrayName 为数组名，length 为数组长度。 需要注意的是：
- 在不支持C99的编译器中，length 必须是一个数值常量，不能是变量，例如 VC6.0、VS2010 等；在支持C99的编译器中，length 还可以是变量，例如 C-Free 5.0、GCC等。
- 数组在内存中占用一段连续的空间，数组名表示的是这段内存空间的首地址。
2) 访问数组中某个元素的格式为：
arrayName[index]index 为数组下标。注意 index 的值必须大于等于零，并且小于数组长度，否则会发生数组越界，出现意想不到的错误。
3) 可以对数组中的单个元素赋值，也可以整体赋值，例如：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_comment" style="color: rgb(56, 173, 36);">// 对单个元素赋值</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;">a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;">a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;">a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">2</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">34</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_comment" style="color: rgb(56, 173, 36);">// 整体赋值（不指明数组长度）</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">float</span> b<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span> <span class="sh_number" style="color: rgb(50, 186, 6);">23.3</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100.00</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0.34</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_comment" style="color: rgb(56, 173, 36);">// 整体赋值（指明数组长度）</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> m<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span> <span class="sh_number" style="color: rgb(50, 186, 6);">100</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">30</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_number" style="color: rgb(50, 186, 6);">234</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_comment" style="color: rgb(56, 173, 36);">// 字符数组赋值</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str1<span class="sh_symbol" style="color: rgb(48, 48, 238);">[]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_string" style="color: rgb(24, 97, 167);">"http://c.biancheng.net"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_comment" style="color: rgb(56, 173, 36);">// 将数组所有元素都初始化为0</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> arr<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">char</span> str2<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">20</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li></ol>数组应用举例
【示例1】求一个整型数组中的最大值和最小值。<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> max<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> min<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//从控制台获取用户输入并赋值给数组元素</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">scanf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">&</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//假设a[0]是最大值也是最小值</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> max <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">],</span> min <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span><span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">for</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> i<span class="sh_symbol" style="color: rgb(48, 48, 238);">++)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">></span> max<span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> max <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">]</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);"><</span> min<span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> min <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">[</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">];</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"The max is %d, The min is %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> max<span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> min<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>2 123 45 100 575 240 799 710 10 90↙
The max is 799, The min is 2
这段代码有两点需要说明：
1) 从控制台获取数组元素时，我们一次性输入10个整数才按下回车键，而不是每输入一个整数就按一次回车键，这正是利用了标准输入缓冲区。
2) 要想求得数组中的最大值和最小值，就得循环比较数组中的所有元素，并设置两个变量 max 和 min 来接收。以最大值为例，开始循环之前，先假设第0个元素是最大值（当然你也可以假设第1、2、3 个元素），然后用 max 和数组中剩余的元素进行比较，如果某个元素的值比 max 大，就用这个元素的值替换 max 的值，等把所有元素遍历完了，max 中就是最大值了。
关于排序和查找
学完了数组，有两个重要的知识点要求大家掌握，那就是排序（Sort）和查找（Search），比如：- 给你 10 个打乱顺序的整数，要能够按照从小到大或者从大到小的顺序输出；
- 给定一个字符串 str1，以及一个子串 str2，要能够判断 str2 是否在 str1 中。
10.C语言非阻塞式键盘监听
监听键盘可以使用C语言的字符输入函数，例如 getchar、getch、getche 等，我们会在《结合缓冲区谈谈C语言getchar()、getche()、getch()的区别》一节中重点讲解它们的区别。
使用getche函数监听键盘的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><conio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> ch<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//循环监听，直到按Esc键退出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">while</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>ch <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_function" style="color: rgb(209, 28, 237);">getch</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">())</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>ch <span class="sh_symbol" style="color: rgb(48, 48, 238);">==</span> <span class="sh_number" style="color: rgb(50, 186, 6);">27</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">break</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span><span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">else</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Number: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">++</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Number: 1 //按下任意键
Number: 2 //按下任意键
Number: 3
Number: 4
Number: 5 //按下Esc键
这段代码虽然达到了监听键盘的目的，但是每次都必须按下一个键才能执行getch后面的代码，也就是说，getch后面的代码被阻塞了。
阻塞式键盘监听非常不方便，尤其是在游戏中，往往意味着用户要不停按键游戏才能进行，所以一般采用非阻塞式键盘监听。
使用
conio.h头文件中的kbhit函数可以实现非阻塞式键盘监听。我们每按下一个键，都会将对应的字符放到键盘缓冲区，kbhit 函数会检测缓冲区中是否有字符，如果有字符返回非0值，没有返回0。但是kbhit不会读取字符，字符仍然留在缓冲区。请看下面的例子：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><windows.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><conio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">char</span> ch<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> i <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_comment" style="color: rgb(56, 173, 36);">//循环监听，直到按Esc键退出</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">while</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_number" style="color: rgb(50, 186, 6);">1</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_function" style="color: rgb(209, 28, 237);">kbhit</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">())</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> ch <span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span> <span class="sh_function" style="color: rgb(209, 28, 237);">getch</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">();</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">if</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>ch <span class="sh_symbol" style="color: rgb(48, 48, 238);">==</span> <span class="sh_number" style="color: rgb(50, 186, 6);">27</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">break</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"Number: %d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span> <span class="sh_symbol" style="color: rgb(48, 48, 238);">++</span>i<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">Sleep</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_number" style="color: rgb(50, 186, 6);">1000</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//暂停1秒</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>Number: 1
Number: 2
Number: 3
Number: 4
Number: 5 //按下Esc键
每次循环，kbhit 会检测用户是否按下某个键（也就是检测缓冲区中是否有字符），没有的话继续执行后面的语句，有的话就通过 getch 读取，并判断是否是 Esc，是的话就退出循环，否则继续循环。
kbhit 之所以能够实现非阻塞式监听是因为它只检测字符，而不要求输入字符。
Sleep 是“睡眠”的意思，用来让程序暂停执行一段时间，以毫秒记。
11.C语言获取随机数
可能大家在编程的时候需要电脑来获取一些随机的反应，这个时候我们可以使用随机数，比较常见的是 rand() 函数，它可以随机的产生 0 ~ rand_max 的随机数。rand_max 是一个很大的数字，具体关系到IDE和数据类型，我们一般的需要不可能超出它的范围。
下面是一个实例：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_function" style="color: rgb(209, 28, 237);">rand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">();</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li></ol>编译后再运行几次，你会发现产生的随机数是相同的。实际上，rand() 函数产生的随机数是伪随机数，是根据一个数按照某个公式推算出来的，这个数我们称之为“种子”，但是这个种子在系统启动之后就是一个定值，我们需要用 srand() 来进行播种，即在int a前加一句：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_function" style="color: rgb(209, 28, 237);">srand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">((</span><span class="sh_type" style="color: rgb(207, 149, 17);">unsigned</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_function" style="color: rgb(209, 28, 237);">time</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>NULL<span class="sh_symbol" style="color: rgb(48, 48, 238);">));</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//这里利用时间进行播种，需要time.h</span></li></ol>
这样，我们就能得到不同的随机数，其实C语言中还有一个 random() 函数可以获取随机数，但是 random() 函数不是ANSI C标准，不能在VC等编译器通过，所以比较少用。
那如何产生一定范围的随机数呢？我们可以利用取模的方法：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_function" style="color: rgb(209, 28, 237);">rand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()%</span><span class="sh_number" style="color: rgb(50, 186, 6);">10</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//产生0~9的随机数，注意10会被整除</span></li></ol>
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_function" style="color: rgb(209, 28, 237);">rand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()%</span><span class="sh_number" style="color: rgb(50, 186, 6);">51+13</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span> <span class="sh_comment" style="color: rgb(56, 173, 36);">//产生13~63的随机数</span></li></ol>
最后给出产生 13~63 范围内随机数的完整代码：
<ol class="snippet-num" style="margin-top: 0px; margin-bottom: 0px; margin-left: 0px; padding-left: 20px; padding-top: 3px !important; padding-right: 8px !important; padding-bottom: 3px !important;"><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdio.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_preproc" style="color: rgb(83, 116, 176);">#include</span> <span class="sh_string" style="color: rgb(24, 97, 167);"><stdlib.h></span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_type" style="color: rgb(207, 149, 17);">int</span> <span class="sh_function" style="color: rgb(209, 28, 237);">main</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()</span><span class="sh_cbracket" style="color: rgb(48, 48, 238);">{</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_type" style="color: rgb(207, 149, 17);">int</span> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">srand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">((</span><span class="sh_type" style="color: rgb(207, 149, 17);">unsigned</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">)</span><span class="sh_function" style="color: rgb(209, 28, 237);">time</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span>NULL<span class="sh_symbol" style="color: rgb(48, 48, 238);">));</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> a<span class="sh_symbol" style="color: rgb(48, 48, 238);">=</span><span class="sh_function" style="color: rgb(209, 28, 237);">rand</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">()%</span><span class="sh_number" style="color: rgb(50, 186, 6);">51+13</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_function" style="color: rgb(209, 28, 237);">printf</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">(</span><span class="sh_string" style="color: rgb(24, 97, 167);">"%d</span><span class="sh_specialchar" style="color: rgb(24, 97, 167);">\n</span><span class="sh_string" style="color: rgb(24, 97, 167);">"</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">,</span>a<span class="sh_symbol" style="color: rgb(48, 48, 238);">);</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"> <span class="sh_keyword" style="color: rgb(255, 48, 48); font-weight: bold;">return</span> <span class="sh_number" style="color: rgb(50, 186, 6);">0</span><span class="sh_symbol" style="color: rgb(48, 48, 238);">;</span></li><li style="padding-left: 8px; list-style: decimal-leading-zero outside none;"><span class="sh_cbracket" style="color: rgb(48, 48, 238);">}</span></li><li></li></ol> 0 0
- C语言数组的概念
- C语言指针数组的概念
- 62 C语言数组的概念
- C语言中指针数组的概念和定义
- C语言中最难分辨的概念--”数组与指针“
- c语言数组相关内存的一些概念
- 【C语言提高31】数组基础概念
- C语言：C语言指针的概念
- C语言的重要概念
- c语言的重要概念
- Ｃ语言的重要概念
- Ｃ语言的重要概念
- c语言的重要概念
- c语言的重要概念
- c语言的一些概念
- C语言的重要概念
- c语言的重要概念
- C语言的重要概念
- Linux文件夹解释大全
- JDBC学习（1）数据库驱动的下载和导入
- 导入Excle
- android 中的layer图层
- 小工具 - 批量删除Maven下载失败的文件夹
- C语言数组的概念
- 1619-7 张良 十一月八号总结 ［连续第三十九天］
- BZOJ 4144 Dijkstra+Kruskal+倍增LCA
- 371.Print Numbers by Recursion-用递归打印数字（中等题）
- 20161108学习心得
- 学习制作GUI界面
- ajax请求状态:readyState的状态值，status状态值
- caffe python layer
- win7 cmd 里 找不到 没有 ping 命令 的 解决方法
