117 lines
6.8 KiB
HTML
117 lines
6.8 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>strdup</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_experimental_dynamic_strdup skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading">strdup</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-experimental.html">experimental</a>‎ | <a href="c-experimental-dynamic.html">dynamic</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><string.h></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td>
|
|
<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span> strdup<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str1 <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-dynamic-tr t-mark-ts">(动态内存 TR)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>返回指向空终止字符串的指针，字符串是 <code>str1</code> 所指向字符串的副本。返回的指针必须传递给 <span class="t-lc"><a href="c-memory-free.html">free</a></span> 以避免内存泄漏。</p>
|
|
<p>若错误发生，则返回空指针，并可能设置 <span class="t-lc"><a href="c-error-errno.html">errno</a></span> 。</p>
|
|
<p>同所有来自动态内存 TR 的函数， <code>strdup</code> 仅若实现定义了 <span class="t-c"><span class="mw-geshi c source-c">__STDC_ALLOC_LIB__</span></span> 且用户在包含 <code>string.h</code> 前定义 <span class="t-c"><span class="mw-geshi c source-c">__STDC_WANT_LIB_EXT2__</span></span> 为整数常量 <span class="t-c"><span class="mw-geshi c source-c"><span class="nu0">1</span></span></span> 才保证可用。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>str1</td>
|
|
<td>-</td>
|
|
<td>指向要被复制的空终止字符串的指针</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>指向新分配字符串的指针，若出现错误则为空指针。</p>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>此函数等同于 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strdup.html">POSIX strdup</a> 。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#ifdef __STDC_ALLOC_LIB__</span>
|
|
<span class="co2">#define __STDC_WANT_LIB_EXT2__ 1</span>
|
|
<span class="co2">#else</span>
|
|
<span class="co2">#define _POSIX_C_SOURCE 200809L</span>
|
|
<span class="co2">#endif</span>
|
|
|
|
<span class="co2">#include <string.h></span>
|
|
<span class="co2">#include <assert.h></span>
|
|
<span class="co2">#include <stdlib.h></span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>s1 <span class="sy1">=</span> <span class="st0">"String"</span><span class="sy4">;</span>
|
|
<span class="kw4">char</span> <span class="sy2">*</span>s2 <span class="sy1">=</span> strdup<span class="br0">(</span>s1<span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="c-error-assert.html"><span class="kw407">assert</span></a><span class="br0">(</span><a href="c-string-byte-strcmp.html"><span class="kw559">strcmp</span></a><span class="br0">(</span>s1, s2<span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">0</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="c-memory-free.html"><span class="kw406">free</span></a><span class="br0">(</span>s2<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-experimental-dynamic-strndup.html"><span class="t-lines"><span>strndup</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-dynamic-tr t-mark-ts">(动态内存 TR)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>分配字符串副本，至多到指定的大小<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-string-byte-strcpy.html"><span class="t-lines"><span>strcpy</span><span>strcpy_s</span></span></a></div>
|
|
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>复制一个字符串给另一个<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="c-memory-malloc.html"><span class="t-lines"><span>malloc</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>分配内存<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|