213 lines
15 KiB
HTML
213 lines
15 KiB
HTML
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<title>strerror, strerror_s, strerrorlen_s</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_string_byte_strerror skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading">strerror, strerror_s, strerrorlen_s</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-string.html">string</a>‎ | <a href="c-string-byte.html">byte</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<td>
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<div>定义于头文件 <code><string.h></code></div>
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</td>
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<td></td>
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<td></td>
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span><span class="sy2">*</span> strerror<span class="br0">(</span> <span class="kw4">int</span> errnum <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td class="t-dcl-nopad"></td>
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<tr class="t-dcl t-since-c11">
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<td>
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<div><span class="mw-geshi c source-c">errno_t strerror_s<span class="br0">(</span> <span class="kw4">char</span> <span class="sy2">*</span>buf, rsize_t bufsz, errno_t errnum <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-c11">(C11 起)</span></td>
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<tr class="t-dcl t-since-c11">
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<div><span class="mw-geshi c source-c"><a href="c-types-size_t.html"><span class="kw100">size_t</span></a> strerrorlen_s<span class="br0">(</span> errno_t errnum <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-c11">(C11 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tbody>
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<div class="t-li1"><span class="t-li">1)</span> 返回指向系统错误码 <code>errnum</code> 的文本表示的指针，它等同于 <span class="t-lc"><a href="c-io-perror.html">perror()</a></span> 会打印的描述。</div>
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<div class="t-li1"><span class="t-li"></span> <code>errnum</code> 通常获得自 <code>errno</code> 对象，不过函数接受任何 <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">int</span></span></span> 类型值。字符串的内容是本地环境限定的。</div>
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<div class="t-li1"><span class="t-li"></span> 程序必须不修改返回的字符串，但对 <code>strerror</code> 函数的后继调用可能重写该字符串。不要求 <code>strerror</code> 为线程安全。实现可以返回指向静态只读字符串字面量的不同指针，或反复返回指向静态缓冲区的同一指针， strerror 放置字符串于该缓冲区中。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，除了将消息复制到用户提供的存储 <code>buf</code> 中。不写入多于 <code>bufsz-1</code> 个字符，缓冲区始终为空终止的。若消息必须被截断，且 <code>bufsz</code> 大于 3 ，则只写入 <code>bufsz-4</code> 个字符，并在空终止符前前附字符 <span class="t-c"><span class="mw-geshi c source-c"><span class="st0">"..."</span></span></span> 。另外，在运行时检测下列错误，并调用当前安装的<a href="c-error-set_constraint_handler_s.html">制约处理</a>函数：
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<dl>
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<dd>
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<ul>
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<li><code>buf</code> 为空指针</li>
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<li><code>bufsz</code> 为零或大于 <span class="t-lc">RSIZE_MAX</span></li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-li1"><span class="t-li"></span> 若到 <code>buf</code> 的写入出现在数组末尾后则行为未定义，这在 <code>buf</code> 所指向的缓冲区大小写小于错误消息的字符数，且小于 <code>bufsz</code> 时发生。</div>
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<div class="t-li1"><span class="t-li">3)</span> 计算若以 <code>errnum</code> 调用则 <code>strerror_s</code> 本会写入的，本地环境限定错误消息的不截断长度。长度不包含空终止符。
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<dl>
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<dd></dd>
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<dd>同所有边界检查函数， <code>strerror_s, strerrorlen_s</code> 仅若实现定义了 <span class="t-c"><span class="mw-geshi c source-c">__STDC_LIB_EXT1__</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_EXT1__</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。</dd>
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</dl>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>errnum</td>
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<td>-</td>
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<td>指代错误码的整数值</td>
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</tr>
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<tr class="t-par">
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<td>buf</td>
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<td>-</td>
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<td>指向用户提供的缓冲区的指针</td>
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</tr>
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<tr class="t-par">
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<td>bufsz</td>
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<td>-</td>
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<td>用户提供的缓冲区的大小</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<div class="t-li1"><span class="t-li">1)</span> 指向对应 <span class="t-lc"><a href="c-error-errno.html">errno</a></span> 错误码 <code>errnum</code> 的空终止字节串的指针。</div>
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<div class="t-li1"><span class="t-li">2)</span> 若整个消息完整存储于 <code>buf</code> 则为零，否则为非零。</div>
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<div class="t-li1"><span class="t-li">3)</span> <code>strerror_s</code> 会返回的消息长度（不包含空终止符）</div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p><a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strerror.html">POSIX</a> 允许对 <code>strerror</code> 的后继调用非法化先前调用所返回的指针值。它亦指定控制这些消息的 <a href="c-locale-LC_categories.html"><tt>LC_MESSAGES</tt></a> 本地环境平面。</p>
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<p><code>strerror_s</code> 是仅有的允许截断的带边界检查函数，因为提供尽可能多的关于失败的信息被视为更加令人满意。 POSIX 亦为类似目的定义 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strerror.html">strerror_r</a> 。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="c source-c">
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<pre class="de1"><span class="co2">#define __STDC_WANT_LIB_EXT1__ 1</span>
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<span class="co2">#include <stdio.h></span>
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<span class="co2">#include <errno.h></span>
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<span class="co2">#include <string.h></span>
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<span class="co2">#include <locale.h></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span>fp <span class="sy1">=</span> <a href="c-io-fopen.html"><span class="kw818">fopen</span></a><span class="br0">(</span><a href="c-io-tmpnam.html"><span class="kw882">tmpnam</span></a><span class="br0">(</span><span class="br0">(</span><span class="kw4">char</span><span class="br0">[</span><a href="c-io.html"><span class="kw899">L_tmpnam</span></a><span class="br0">]</span><span class="br0">)</span><span class="br0">{</span><span class="nu0">0</span><span class="br0">}</span><span class="br0">)</span>, <span class="st0">"r"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fp<span class="sy1">==</span><a href="c-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span> <span class="br0">{</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"File opening error: %s<span class="es1">\n</span>"</span>, strerror<span class="br0">(</span><span class="kw2">errno</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-locale-setlocale.html"><span class="kw900">setlocale</span></a><span class="br0">(</span>LC_MESSAGES, <span class="st0">"de_DE.utf8"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Now in German: %s<span class="es1">\n</span>"</span>, strerror<span class="br0">(</span><span class="kw2">errno</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co2">#ifdef __STDC_LIB_EXT1__</span>
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<a href="c-locale-setlocale.html"><span class="kw900">setlocale</span></a><span class="br0">(</span><a href="c-locale-LC_categories.html"><span class="kw903">LC_ALL</span></a>, <span class="st0">"zh_CN.utf8"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// printf 需要多字节输出的 CTYPE</span>
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<a href="c-types-size_t.html"><span class="kw100">size_t</span></a> errmsglen <span class="sy1">=</span> strerrorlen_s<span class="br0">(</span><span class="kw2">errno</span><span class="br0">)</span> <span class="sy2">+</span> <span class="nu0">1</span><span class="sy4">;</span>
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<span class="kw4">char</span> errmsg<span class="br0">[</span>errmsglen<span class="br0">]</span><span class="sy4">;</span>
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strerror_s<span class="br0">(</span>errmsg, errmsglen, <span class="kw2">errno</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Now in Chinese: %s<span class="es1">\n</span>"</span>, errmsg<span class="br0">)</span><span class="sy4">;</span>
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<span class="co2">#endif</span>
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<span class="br0">}</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">File opening error: No such file or directory
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Now in German: Datei oder Verzeichnis nicht gefunden
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Now in Chinese: 没有那个文件或目录</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准（ISO/IEC 9899:2011）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.24.6.2 The strerror function (p: 371)</li>
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</ul>
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</dd>
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</dl>
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<dl>
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<dd>
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<ul>
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<li>K.3.7.4.2 The strerror_s function (p: 622)</li>
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</ul>
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</dd>
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</dl>
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<dl>
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<dd>
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<ul>
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<li>K.3.7.4.3 The strerrorlen_s function (p: 623)</li>
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</ul>
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</dd>
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</dl>
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<div class="t-ref-std-c99">
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<ul>
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<li>C99 标准（ISO/IEC 9899:1999）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.21.6.2 The strerror function (p: 334)</li>
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</ul>
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</dd>
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</dl>
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<div class="t-ref-std-c89">
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<ul>
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<li>C89/C90 标准（ISO/IEC 9899:1990）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>4.11.6.2 The strerror function</li>
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</ul>
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</dd>
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</dl>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-io-perror.html"><span class="t-lines"><span>perror</span></span></a></div>
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</div>
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</td>
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<td>显示对应当前错误的字符串到 <span class="t-lc"><a href="c-io.html">stderr</a></span><br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-error-errno.html"><span class="t-lines"><span>errno</span></span></a></div>
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</div>
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</td>
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<td>展开成 POSIX 兼容的线程局域错误编号变量<br />
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<span class="t-mark">(宏变量)</span></td>
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</tr>
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</table>
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</div>
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</div>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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