Linux C字符串替换函数实例详解
<p><strong>Linux C字符串替换函数实例详解</strong></p>
<p>
最近学习linux 的基础编程知识，字符串替换函数，在网上找下资料，觉得这篇文章写的不错，记录下来，和大家分享一下：</p>
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实例代码：</p>
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<code class="cpp preprocessor">#include <stdio.h></code>
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<code class="cpp preprocessor">#include <string.h></code>
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<code class="cpp preprocessor">#include <stdlib.h></code>
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<code class="cpp spaces"> </code>
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<code class="cpp comments">/**</code>
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<code class="cpp comments">*</code>
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<code class="cpp comments">* @author: cnscn@163.com</code>
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<code class="cpp comments">* @reference: lovesnow1314@http://community.csdn.net/Expert/TopicView3.asp?id=5198221 </code>
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<code class="cpp comments">*</code>
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<code class="cpp comments">* 用新子串newstr替换源字符串src中的前len个字符内所包含的oldstr子串</code>
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<code class="cpp comments">*</code>
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<code class="cpp comments">* @param char* dest 目标串，也就是替换后的新串</code>
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<code class="cpp comments">* @param const char* src 源字符串，被替换的字符串</code>
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<code class="cpp comments">* @param const char* oldstr 旧的子串，将被替换的子串</code>
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<code class="cpp comments">* @param const char* newstr 新的子串</code>
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<code class="cpp comments">* @param int len 将要被替换的前len个字符</code>
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<code class="cpp comments">*</code>
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<code class="cpp comments">* @return char* dest 返回新串的地址</code>
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<code class="cpp comments">*</code>
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<code class="cpp comments">*/</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*strreplace(</code><code class="cpp color1 bold">char</code> <code class="cpp plain">*dest, </code><code class="cpp color1 bold">char</code> <code class="cpp plain">*src, </code><code class="cpp keyword bold">const</code> <code class="cpp color1 bold">char</code> <code class="cpp plain">*oldstr, </code><code class="cpp keyword bold">const</code> <code class="cpp color1 bold">char</code> <code class="cpp plain">*newstr, </code><code class="cpp color1 bold">size_t</code> <code class="cpp plain">len)</code>
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<code class="cpp plain">{</code>
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<code class="cpp comments">//如果串相等，则直接返回</code>
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<code class="cpp keyword bold">if</code><code class="cpp plain">(</code><code class="cpp functions bold">strcmp</code><code class="cpp plain">(oldstr, newstr)==0)</code>
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<code class="cpp keyword bold">return</code> <code class="cpp plain">src;</code>
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<code class="cpp comments">//子串位置指针</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*needle;</code>
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<code class="cpp comments">//临时内存区</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*tmp;</code>
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<code class="cpp comments">//把源串地址赋给指针dest，即让dest和src都指向src的内存区域</code>
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<code class="cpp plain">dest = src;</code>
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<code class="cpp comments">//如果找到子串, 并且子串位置在前len个子串范围内, 则进行替换, 否则直接返回</code>
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<code class="cpp keyword bold">while</code><code class="cpp plain">((needle = </code><code class="cpp functions bold">strstr</code><code class="cpp plain">(dest, oldstr)) && (needle -dest <= len))</code>
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<code class="cpp plain">{</code>
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<code class="cpp comments">//分配新的空间: +1 是为了添加串尾的'\0'结束符</code>
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<code class="cpp plain">tmp=(</code><code class="cpp color1 bold">char</code><code class="cpp plain">*)</code><code class="cpp functions bold">malloc</code><code class="cpp plain">(</code><code class="cpp functions bold">strlen</code><code class="cpp plain">(dest)+(</code><code class="cpp functions bold">strlen</code><code class="cpp plain">(newstr)-</code><code class="cpp functions bold">strlen</code><code class="cpp plain">(oldstr))+1);</code>
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<code class="cpp comments">//把src内的前needle-dest个内存空间的数据，拷贝到arr</code>
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<code class="cpp functions bold">strncpy</code><code class="cpp plain">(tmp, dest, needle-dest);</code>
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<code class="cpp comments">//标识串结束</code>
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<code class="cpp plain">tmp=</code><code class="cpp string">'\0'</code><code class="cpp plain">;</code>
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<code class="cpp comments">//连接arr和newstr, 即把newstr附在arr尾部, 从而组成新串(或说字符数组)arr</code>
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<code class="cpp functions bold">strcat</code><code class="cpp plain">(tmp, newstr);</code>
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<code class="cpp comments">//把src中 从oldstr子串位置后的部分和arr连接在一起，组成新串arr</code>
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<code class="cpp functions bold">strcat</code><code class="cpp plain">(tmp, needle+</code><code class="cpp functions bold">strlen</code><code class="cpp plain">(oldstr));</code>
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<code class="cpp comments">//把用malloc分配的内存，复制给指针retv</code>
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<code class="cpp plain">dest = strdup(tmp);</code>
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<code class="cpp comments">//释放malloc分配的内存空间</code>
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<code class="cpp functions bold">free</code><code class="cpp plain">(tmp);</code>
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<code class="cpp plain">}</code>
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<code class="cpp keyword bold">return</code> <code class="cpp plain">dest;</code>
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<code class="cpp plain">}</code>
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<code class="cpp color1 bold">int</code> <code class="cpp plain">main()</code>
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<code class="cpp plain">{</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*str=</code><code class="cpp string">"wo i love iyou"</code><code class="cpp plain">;</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*old=</code><code class="cpp string">"i"</code><code class="cpp plain">;</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*</code><code class="cpp keyword bold">new</code><code class="cpp plain">=</code><code class="cpp string">"ILOVEYOUYA"</code><code class="cpp plain">;</code>
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<code class="cpp color1 bold">char</code> <code class="cpp plain">*dest;</code>
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<code class="cpp comments">//分配内存空间: 大小 == src的长度 ＋ newstr和oldstr长度差(可能是正负或0)+1</code>
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<code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%s\n"</code><code class="cpp plain">,strreplace(dest, str, old, </code><code class="cpp keyword bold">new</code><code class="cpp plain">,1));</code>
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<code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%s\n"</code><code class="cpp plain">,strreplace(dest, str, old, </code><code class="cpp keyword bold">new</code><code class="cpp plain">,5));</code>
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<code class="cpp functions bold">printf</code><code class="cpp plain">(</code><code class="cpp string">"%s\n"</code><code class="cpp plain">,strreplace(dest, str, old, </code><code class="cpp keyword bold">new</code><code class="cpp plain">,40));</code>
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<code class="cpp keyword bold">return</code> <code class="cpp plain">0;</code>
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<code class="cpp plain">}</code>
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