C语言--一维数组,字符数组

#import <Foundation/Foundation.h>int main(int argc, const char * argv[]){#pragma mark----------数组   //数组是容器,相同数据类型    //构造类型    //    int  a[3]={5,2,0};    //类型//    int[3];    //变量名//    a;    //初值//    {5,2,0};        //    int a[4] = {9,8,7,6};//    float b[6] = {2.5,3.14};//    char c[3] = "abc";//    char d[3] = {'a','b','c'};//    BOOL e[4] = {YES,NO};        //a[0]+a[1]操作数组下标取值赋值        //前有类型修饰符,代表数组,没有类型修饰符,代表下标        //1.生成一个包含20个元素数组,数组的值取值在30到70之间,并求出数组元素的和//    int sum = 0, a[20]={0};//    for (int i = 0; i<20; i++) {//        a[i]=arc4random()%41+30;//        printf("%d ",a[i]);//        sum = sum + a[i];//    }//    printf("\nsum=%d",sum);    //2.复制//    int a[20]={0},b[20]={0};//    for (int i = 0; i<20; i++) {//        a[i]=arc4random()%41+30;//        printf("%d ",a[i]);//        b[i]=a[i];//    }//    printf("\n");//    for (int j = 0; j<20; j++) {//        printf("%d ",b[j]);//    }    //3.生成两个数组,然后两个数组对应下标元素相加,放到第三个数组中//    int a[10]={0},b[10]={0},c[10]={0};//    for (int i = 0; i<10; i++) {//        a[i]=arc4random()%(40-20+1)+20;//        b[i]=arc4random()%(40-20+1)+20;//        c[i]=a[i]+b[i];//          printf("%d + %d = %d\n",a[i],b[i],c[i]);//    }//    printf("\n");//    for (int j = 0; j<10; j++) {//            printf("%d ",b[j]);//    }//    printf("\n");//    for (int j = 0; j<10; j++) {//        printf("%d ",c[j]);//    }    #pragma mark--------------1    //注意,    //1,系统不会检测数组元素的下标是否越界,编程时,必须保证数组下标不能越界    //2,数组是一个整体,不能直接参加运算,只能对单个元素进行处理,通常会用到数组的地方,就会用到循环(循环就是为了数组而生)    //    scanf("%d",&a);//    getchar() 打印123def 结果是1//    printf(""),打印123def 结果是123        /**     *  从键盘缓冲区读取数据     */        //    int a[10]={0};//    for (int i = 0; i<10; i++) {//        a[i]=arc4random()%31;//        printf("%2d ",a[i]);//    }//    for (int i = 0; i<10-1; i++) {//        for (int j = 0; j<10-1-i; j++) {//            if (a[j]>a[j+1]) {//                int temp = a[j];//                a[j]=a[j+1];//                a[j+1]=temp;//            }//        }//    }//    printf("\n");//    for (int i =0; i<10; i++) {//        printf("%-2d ",a[i]);//    }    //    int a[10]={0};//    for (int i = 0; i<10; i++) {//        a[i]=arc4random()%(40-20+1)+20;//        printf("%d ",a[i]);//    }//    for (int i = 0; i<10-1; i++) {//        for (int j = 0; j<10-1-i; j++) {//            if (a[j]>a[j+1]) {//max<a[i],min>a[i]//                int temp = a[j];//                a[j]=a[j+1];//                a[j+1]=temp;//            }//        }//    }//    printf("\n");//    for (int i =0; i<10; i++) {//        printf("%d ",a[i]);//    }    //    strlen("hello");#pragma mark--------------2    //字符串长度  比如hello,字符串长度5//    printf("%lu",strlen("hello"));    //字符串所占空间 比如char[10]="hello" 字符串所占空间10;//    char c[] = "hello";//    printf("%lu",sizeof(c));//    for (int i = 0; i<sizeof(c); i++) {//        printf(" %c ",c[i]);//    }//    printf("\n%s ",c);    //等同于下面    //%s,从首地址开始打印,直到打到/0结束//    char d = 0;//    int i = 0;//    while ((d = c[i]) != '\0') {//        printf("%c",d);//        i++;//    }    //strlen,测量字符串长度    //strcpy    //strcmp,比较    //strcat//拼接//    char name[20]="zuoyoudong";//    printf("%s length = %lu",name,strlen(name));//    int i = 0;//    while (name[i] !='\0') {//        printf("%c",name[i]);//        i++;//    }//    printf("%d",i);        //    char z[]="zuo";//    char y[5]="yi";//    strcpy(y, z);//    printf("%s",strcpy(y, z));    //1,"hello",2,"abcdefghi",3,拷贝,hello\0ghi#pragma mark--------------3//    char str1[50] = "hangsan";//    char str2[10] = "lisi";//    strcpy(str2, str1);//前面目的串,后面来源串,const只可读,不可赋值//    printf("%s",str2);            //字符串拼接strcat 注意:是否有足够的空间,放长度//    strcat(str1, str2);//带const修饰是不变的//    strcat(str1, str2);//    printf("%s",str1);            //字符串比较strcmp(按ASC码值求大小)//    int result = strcmp(str1, str2);//    printf("%d",strcmp(str1, str2));//    printf("%d",result);//    if (result>1) {//        printf("\n%s 大于 %s",str1,str2);//    }else if (result==0){//        printf("%s 等于 %s",str1,str2);//    }else{//        printf("\n%s 小于 %s",str1,str2);//    }            //strlen    //strcmp    //strcat    //strcpy                //查找字符串中的空格数//    char str[50] = "I love iOS,i want an iPhone5s";//    int i = 0,count = 0;//    while (str[i]!='\0') {//        char c = str[i];//        if (c ==' ') {//            count++;//        }//        i++;//    }//    printf("%d",count);#pragma mark--------------4    //把字符倒转过来    //解题思路!    //凡是交换要定义第三方temp    char str1[]="hello";    char str2[5]=" ";    long length = strlen(str1);//    printf("%lu",length);    printf("%lu",sizeof(str1));//    long length =strlen(str1);//    printf("%lu",length);//    int  i = 0;//    while (str1[i] !='\0') {//        char temp = str1[i];//        str1[i]=str2[i];//        str2[i]=temp;//        //    }//    printf("%s",str2);//    for (int i = 0; i<sizeof(str1); <#increment#>) {//        <#statements#>//    }//#pragma mark--------------5绝对值//#pragma mark--------------6for循环//#pragma mark--------------7作业