110 lines
8.6 KiB
HTML
110 lines
8.6 KiB
HTML
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<title>std::tmpnam</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_c_tmpnam skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>tmpnam</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-io.html">io</a>‎ | <a href="cpp-io-c.html">c</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-cstdio.html"><cstdio></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><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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<p>创建不指名当前存在的文件的独有文件名，并将它存储于 <code>filename</code> 所指向的字符串。函数足以生成至多 <span class="t-lc"><a href="cpp-io-c.html">TMP_MAX</a></span> 个独有的文件名，但其一些或全部可能已在使用中，从而不适合作为返回值。</p>
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<p><code>std::tmpnam</code> 修改静态状态，而且不要求为线程安全。</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="cpp-io-c.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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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>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。若无法生成适合文件名，则返回空指针。</p>
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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>std::tmpnam</code> 所生成的文件名难以猜测，却可能是另一个进程在 <code>std::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="cpp-io-c-tmpfile.html">std::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>std::tmpnam</code> ）。</p>
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<p>POSIX 系统额外定义名称类似的函数 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/tempnam.html"><code>tempnam()</code></a> ，它提供对目录的选择（默认是可选定义的宏 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdio.h.html"><code>P_tmpdir</code></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="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <cstdio></span>
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<span class="co2">#include <string></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> name1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">tmpnam</span><span class="br0">(</span>nullptr<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"temporary file name: "</span> <span class="sy1"><<</span> name1 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="kw4">char</span> name2<span class="br0">[</span><a href="cpp-io-c.html"><span class="kw1892">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>std<span class="sy4">::</span><span class="me2">tmpnam</span><span class="br0">(</span>name2<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"temporary file name: "</span> <span class="sy1"><<</span> name2 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span></pre></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/fileDjwifs
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temporary file name: /tmp/fileEv2bfW</pre></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="cpp-io-c-tmpfile.html"><span class="t-lines"><span>tmpfile</span></span></a></div>
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</div>
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</td>
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<td>创建并打开一个临时、自动移除的文件<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-temp_directory_path.html"><span class="t-lines"><span>temp_directory_path</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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<td>返回一个适用于临时文件的目录<br />
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<span class="t-mark">(函数)</span></td>
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