177 lines
12 KiB
HTML
177 lines
12 KiB
HTML
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>tmpfile, tmpfile_s</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_io_tmpfile 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">tmpfile, tmpfile_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-io.html">io</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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<div>定义于头文件 <code><stdio.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"><a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span>tmpfile<span class="br0">(</span><span class="kw4">void</span><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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<div><span class="mw-geshi c source-c">errno_t tmpfile_s<span class="br0">(</span><a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span> <span class="kw4">restrict</span> <span class="sy2">*</span> <span class="kw4">restrict</span> streamptr<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-sep">
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<td></td>
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<div class="t-li1"><span class="t-li">1)</span> 创建并打开一个临时文件。该文件作为二进制文件、更新模式（如同为 <span class="t-lc"><a href="c-io-fopen.html">fopen</a></span> 以 <code>"wb+"</code> 模式）打开。该文件的文件名保证在文件系统中唯一。至少可以在程序的生存期内能打开 <span class="t-lc"><a href="c-io.html">TMP_MAX</a></span> 个文件（此极限可能与 <span class="t-lc"><a href="c-io-tmpnam.html">tmpnam</a></span> 共享，并可能为 <span class="t-lc"><a href="c-io.html">FOPEN_MAX</a></span> 所进一步限制）。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，除了至少可以打开 <span class="t-lc">TMP_MAX_S</span> 个文件（此极限可能与 <span class="t-lc">tmpnam_s</span> 共享），而若 <code>streamptr</code> 为空指针，则调用当前安装的<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></dd>
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<dd>同所有边界检查函数， <code>tmpfile_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><stdio.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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<p>此函数创建的临时文件在程序正常退出时被关闭并删除。它在程序异常终止时是否被删除是实现定义的。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<div class="t-li1"><span class="t-li">1)</span> （无）</div>
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<div class="t-li1"><span class="t-li">2)</span> 指向此函数调用将要更新的指针的指针</div>
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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> 指向与文件关联的文件流的指针，或若出现错误则为空指针。</div>
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<div class="t-li1"><span class="t-li">2)</span> 若成功创建并打开文件则为零，若未创建或打开文件，或若 <code>streamptr</code> 为空指针则为非零。另外，成功时存储指向关联文件流的指针到 <code>*streamptr</code> ，而错误时存储空指针值到 <code>*streamptr</code> 。</div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>一些实现（如 Linux ）上，此函数确实从文件系统上创建、打开并立即删除该文件：只要被删除文件的文件开启描述符为程序所管理，该文件就会存在，但只要它被删除，其名就不会出现于任何目录中，从而再无其他进程能打开它。一旦文件描述符被关闭，或一旦程序终止（正常或异常），该文件所占有的空间将被文件系统回收。</p>
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<p>一些实现（如 Windows ）上要求提升的权限，因为该函数可能在系统目录中创建临时文件。</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 _POSIX_C_SOURCE 200112L</span>
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<span class="co2">#include <stdio.h></span>
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<span class="co2">#include <unistd.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> tmpf <span class="sy1">=</span> tmpfile<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fputs.html"><span class="kw832">fputs</span></a><span class="br0">(</span><span class="st0">"Hello, world"</span>, tmpf<span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-rewind.html"><span class="kw875">rewind</span></a><span class="br0">(</span>tmpf<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">char</span> buf<span class="br0">[</span><span class="nu0">6</span><span class="br0">]</span><span class="sy4">;</span>
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<a href="c-io-fgets.html"><span class="kw829">fgets</span></a><span class="br0">(</span>buf, <span class="kw4">sizeof</span> buf, tmpf<span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"got back from the file: '%s'<span class="es1">\n</span>"</span>, buf<span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 展示临时文件名的 Linux 特定方法</span>
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<span class="kw4">char</span> fname<span class="br0">[</span><a href="c-io.html"><span class="kw890">FILENAME_MAX</span></a><span class="br0">]</span>, link<span class="br0">[</span><a href="c-io.html"><span class="kw890">FILENAME_MAX</span></a><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">0</span><span class="br0">}</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw853">sprintf</span></a><span class="br0">(</span>fname, <span class="st0">"/proc/self/fd/%d"</span>, fileno<span class="br0">(</span>tmpf<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>readlink<span class="br0">(</span>fname, link, <span class="kw4">sizeof</span> link <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span> <span class="sy1">></span> <span class="nu0">0</span><span class="br0">)</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"File name: %s<span class="es1">\n</span>"</span>, link<span class="br0">)</span><span class="sy4">;</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">got back from the file: 'Hello'
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File name: /tmp/tmpfjptPe5 (deleted)</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-17">
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<ul>
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<li>C17 标准（ISO/IEC 9899:2018）：</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>7.21.4.3 The tmpfile function (p: 222)</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.3.5.1.1 The tmpfile_s function (p: 427)</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-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>7.21.4.3 The tmpfile function (p: 303)</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.3.5.1.1 The tmpfile_s function (p: 586-587)</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>7.19.4.3 The tmpfile function (p: 269)</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>4.9.4.3 The tmpfile 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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<div class="t-dsc-member-div">
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<div><a href="c-io-tmpnam.html"><span class="t-lines"><span>tmpnam</span><span>tmpnam_s</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div>
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</div>
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</td>
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<td>返回唯一的文件名<br />
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<span class="t-mark">(函数)</span></td>
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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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