174 lines
12 KiB
HTML
174 lines
12 KiB
HTML
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<title>tmpnam, tmpnam_s</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_io_tmpnam skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading">tmpnam, tmpnam_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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<div>定义于头文件 <code><stdio.h></code></div>
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<div><span class="mw-geshi c source-c"><span class="kw4">char</span> <span class="sy2">*</span>tmpnam<span class="br0">(</span> <span class="kw4">char</span> <span class="sy2">*</span>filename <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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<tr class="t-dcl t-since-c11">
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<div><span class="mw-geshi c source-c">errno_t tmpnam_s<span class="br0">(</span><span class="kw4">char</span> <span class="sy2">*</span>filename_s, rsize_t maxsize<span class="br0">)</span><span class="sy4">;</span></span></div>
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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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<div class="t-li1"><span class="t-li">1)</span> 创建独有的合法文件名（长度不长于 <span class="t-lc"><a href="c-io.html">L_tmpnam</a></span> ）并将它存储于 <code>filename</code> 所指向的字符串。此函数足以生成至多 <span class="t-lc"><a href="c-io.html">TMP_MAX</a></span> 个独有文件名，但它们中的一部分可能正在文件系统中使用，从而不适合作为返回值。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，除了至多可以创建 <span class="t-lc">TMP_MAX_S</span> 个长度不长于 <span class="t-lc">L_tmpnam_s</span> 的文件名，而且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>filename_s</code> 是空指针</li>
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<li><code>maxsize</code> 大于 <span class="t-c"><span class="mw-geshi c source-c">RSIZE_MAX</span></span></li>
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<li><code>maxsize</code> 小于生成文件名字符串的长度</li>
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</ul>
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</dd>
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<dd></dd>
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<dd>同所有边界检查函数， <code>tmpnam_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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<p><code>tmpnam</code> 和 <code>tmpnam_s</code> 修改静态状态（可能会在这些函数间共享），而且不要求是线程安全的。</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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<table class="t-par-begin">
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<td>filename</td>
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<td>-</td>
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<td>指向足以保有至少 <span class="t-lc"><a href="c-io.html">L_tmpnam</a></span> 字节的字符数组的指针，将以数组为结果缓冲区。若传递空指针，则返回指向内部静态缓冲区的指针。</td>
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<tr class="t-par">
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<td>filename_s</td>
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<td>-</td>
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<td>指向足以保有至少 <span class="t-lc">L_tmpnam_s</span> 字节的字符数组的指针，将以数组为结果缓冲区。</td>
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</tr>
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<tr class="t-par">
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<td>maxsize</td>
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<td>-</td>
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<td>允许函数写入的最大字节数（典型地为 <code>filename_s</code> 数组的大小）。</td>
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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> 若 <code>filename</code> 不是空指针则为 <code>filename</code> 。否则为指向内部静态缓冲区的指针。若不能生成适合的文件名，则返回空指针。</div>
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<div class="t-li1"><span class="t-li">2)</span> 成功时返回零并将文件名写入 <code>filename_s</code> 。失败时，返回非零并将空字符写入 <code>filename_s[0]</code> （仅若 <code>filename_s</code> 非空且 <code>maxsize</code> 非零且不大于 <span class="t-lc">RSIZE_MAX</span> ）。</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>尽管 <code>tmpnam</code> 所生成的文件名难以猜测，却可能是另一个进程在 <code>tmpnam</code> 返回的时刻和此函程序试图使用返回的名称创建文件之间创建的文件的名称。标准函数 <span class="t-lc"><a href="c-io-tmpfile.html">tmpfile</a></span> 和 POSIX 函数 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mkdtemp.html">mkstemp</a> 无此问题（仅使用 C 标准库创建一个独有的目录仍然要求使用 <code>tmpnam</code> ）。</p>
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<p>POSIX 系统额外定义名称类似的函数 <code><a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/tempnam.html">tempnam()</a></code> ，它提供对目录的选择（默认是可选定义的宏 <code><a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdio.h.html">P_tmpdir</a></code> ）。</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">#include <stdio.h></span>
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<span class="co2">#include <string.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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<span class="kw4">char</span><span class="sy2">*</span> name1 <span class="sy1">=</span> tmpnam<span class="br0">(</span><a href="c-types-NULL.html"><span class="kw103">NULL</span></a><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">"temporary file name: %s<span class="es1">\n</span>"</span>, name1<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">char</span> name2<span class="br0">[</span><a href="c-io.html"><span class="kw899">L_tmpnam</span></a><span class="br0">]</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span>tmpnam<span class="br0">(</span>name2<span class="br0">)</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">"temporary file name: %s<span class="es1">\n</span>"</span>, name2<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">temporary file name: /tmp/fileRZHMwL
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temporary file name: /tmp/file420gSN</pre></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>7.21.4.4 The tmpnam function (p: 303-304)</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.3.5.1.2 The tmpnam_s function (p: 587-588)</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>7.19.4.4 The tmpnam function (p: 269-270)</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>4.9.4.4 The tmpnam 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-tmpfile.html"><span class="t-lines"><span>tmpfile</span><span>tmpfile_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>返回指向临时文件的指针<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 class="visualClear"></div>
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