108 lines
4.4 KiB
HTML
108 lines
4.4 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>CLOCKS_PER_SEC</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_chrono_CLOCKS_PER_SEC 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">CLOCKS_PER_SEC</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-chrono.html">chrono</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><time.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="co2">#define CLOCKS_PER_SEC /*implementation defined*/</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 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>展开成一个 <span class="t-lc"><a href="c-chrono-clock_t.html">clock_t</a></span> 类型的表达式（不必是编译时常量），等于每秒计次数，如 <span class="t-lc"><a href="c-chrono-clock.html">clock()</a></span> 所返回者。</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 定义 <code>CLOCKS_PER_SEC</code> 为一百万，无关乎 <span class="t-lc"><a href="c-chrono-clock.html">clock</a></span> 的实际精度。</p>
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<p>在 C89 中被标准为 <code>CLOCKS_PER_SEC</code> 之前，此宏有时会以其 IEEE std 1003.1-1988 名称 <code>CLK_TCK</code> 为人所用：该名称未包含于 C89 ，并为 POSIX 自身于 1996 年移除，因为它和 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/times.html">times()</a> 函数所用的给出每秒时钟数的宏 <code>_SC_CLK_TCK</code> 有歧义。</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>7.27.1/2 Components of time (p: 388)</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>7.23.1/2 Components of time (p: 338)</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>4.12.1 Components of time</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-chrono-clock.html"><span class="t-lines"><span>clock</span></span></a></div>
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</div>
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</td>
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<td>返回未加工的程序启动时开始经过的处理器时间<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-chrono-clock_t.html"><span class="t-lines"><span>clock_t</span></span></a></div>
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</div>
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</td>
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<td>从时点开始的处理器时间类型<br />
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<span class="t-mark">(typedef)</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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