C++字符串操作集合

本文转自http://blog.csdn.net/liuhuiyan_2014/article/details/46710309

<code class="hljs cpp has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//实现一个函数求字符串的长度。</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> my_length(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (*s == <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span>)<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>+my_length(s + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"123456"</span>;    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_length(s) << endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <assert.h></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//实现一个求字符串的长度。</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> my_length(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (s == NULL)<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> count = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (s[++count] != <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> count;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>;    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_length(s) << endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <string.h></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <assert.h></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>* my_strcpy(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *dist,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *scour){    assert(scour!=NULL);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *p = dist;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (*dist++ = *scour++);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> p;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s1 = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"123"</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s2 = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">strlen</span>(s1)];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_strcpy(s2, s1) << endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <assert.h></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//实现库函数strcat。</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> * my_strcat(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *dist,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> *scour){    assert(dist!=NULL || scour!=NULL);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (*scour == <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span>)<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> dist;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *p = dist;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (*dist != <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span>)dist++;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (*dist++ = *scour++);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> p;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s1 = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">strcpy</span>(s1,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"123"</span>);    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_strcat(s1,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"456"</span>)<<endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <assert.h></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <string.h></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//编写程序使字符串逆序。</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>* my_invert(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s){    assert(s != NULL);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *head = s;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *last = s+<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">strlen</span>(s)-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> temp;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (head < last)    {        temp = *head;        *head = *last;        *last = temp;        head++;        last--;    }    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> s;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> *s = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span>];    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">strcpy</span>(s,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"12345"</span>);    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_invert(s) << endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <iostream></span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include <assert.h></span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">using</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">namespace</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">std</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//模拟实现strchr函数，功能：在一个字符串中查找一个字符第一次出现的位置，如果没有出现返回NULL。</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> my_strchar(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>* dist, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span> ch){    assert(dist!=NULL);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> count = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (*dist != <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span> && *dist!=ch)    {        count++;        dist++;    }    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (*dist == <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'\0'</span>)<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> count+<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main(){    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">cout</span> << my_strchar(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1234"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'1'</span>) << endl;    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"></ul>