121 lines
6.2 KiB
HTML
121 lines
6.2 KiB
HTML
<!DOCTYPE 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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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>fflush</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_io_fflush 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">fflush</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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<tbody>
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<tr class="t-dsc-header">
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<td>
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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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</tr>
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<tr class="t-dcl">
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<td class="t-dcl-nopad">
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<div><span class="mw-geshi c source-c"><span class="kw4">int</span> fflush<span class="br0">(</span> <a href="c-io.html"><span class="kw883">FILE</span></a> <span class="sy2">*</span>stream <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td class="t-dcl-nopad"></td>
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</tr>
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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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</tr>
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</tbody>
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</table>
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<p>对于输出流（及最后操作为输出的更新流），从 <code>stream</code> 的缓冲区写入未写的数据到关联的输出设备。</p>
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<p>对于输入流（及最后操作为输入的更新流），行为未定义。</p>
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<p>若 <code>stream</code> 是空指针，则冲入所有输出流，包括操作于库包内者，或在其他情况下程序无法直接访问者。</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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<tr class="t-par">
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<td>stream</td>
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<td>-</td>
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<td>要写出的文件流</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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<p>成功时返回零。否则返回 <span class="t-lc"><a href="c-io.html">EOF</a></span> 并设置文件流的错误指示器。</p>
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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>POSIX通过定义<code>fflush</code>对输入流的效果<a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fflush.html">扩展它的规定</a>，只要该流还表示一个文件或另一个可定位设备：该情况下重寻位 POSIX 文件指针以匹配 C 流指针（这有效地撤销任何读缓冲），并舍弃任何尚未回读的 <span class="t-lc"><a href="c-io-ungetc.html">ungetc</a></span> 或 <span class="t-lc"><a href="c-io-ungetwc.html">ungetwc</a></span> 的效果。</p>
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<p>微软（Microsoft）也通过定义<code>fflush</code>对输入流的效果扩展它的规定：在Visual Studio 2013及以前的版本中， <a rel="nofollow" class="external text" href="https://docs.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2013/9yky46tz(v=vs.120)">放弃输入缓冲区</a>；在Visual Studio 2015及以后的版本中，<a rel="nofollow" class="external text" href="https://msdn.microsoft.com/en-us/library/9yky46tz.aspx">无影响并保留缓冲区</a>.</p>
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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>7.21.5.2 The fflush function (p: 305)</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>7.19.5.2 The fflush function (p: 270-271)</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>4.9.5.2 The fflush 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-fopen.html"><span class="t-lines"><span>fopen</span><span>fopen_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>打开文件<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-io-fclose.html"><span class="t-lines"><span>fclose</span></span></a></div>
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</div>
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</td>
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<td>关闭文件<br />
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<span class="t-mark">(函数)</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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</div>
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</body>
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</html>
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