143 lines
10 KiB
HTML
143 lines
10 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>mktime</title>
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<link rel="stylesheet" href="site_modules.css" />
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_chrono_mktime 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">mktime</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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<div>定义于头文件 <code><time.h></code></div>
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<td></td>
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<div><span class="mw-geshi c source-c"><a href="c-chrono-time_t.html"><span class="kw523">time_t</span></a> mktime<span class="br0">(</span> <span class="kw1">struct</span> <a href="c-chrono-tm.html"><span class="kw522">tm</span></a> <span class="sy2">*</span><a href="c-chrono-time.html"><span class="kw513">time</span></a> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>重整化表示成 <span class="t-lc"><a href="c-chrono-tm.html">struct tm</a></span> 的本地日历时间，并将其转化成从纪元开始经过时间的 <span class="t-lc"><a href="c-chrono-time_t.html">time_t</a></span> 对象格式。忽略 <code>time->tm_wday</code> 与 <code>time->tm_yday</code> 。容许 <code>time</code> 中的值在其正常范围外。</p>
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<p><code>time->tm_isdst</code> 的负值会导致 <code>mktime</code> 尝试确定在指定时间夏时令是否有效。</p>
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<p>若转换到 <code>time_t</code> 成功，则修改 <code>time</code> 会被修改。更新 <code>time</code> 的所有域为符合其正确范围的值。用可用于其他域的信息重新计算 <code>time->tm_wday</code> 与 <code>time->tm_yday</code> 。</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>time</td>
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<td>-</td>
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<td>指向 <span class="t-lc">struct tm</span> 对象的指针，它指定要转换的本地日历时间</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>成功时返回表示从纪元开始时间的 <span class="t-lc"><a href="c-chrono-time_t.html">time_t</a></span> 对象，若 <code>time</code> 不能表示成 <span class="t-lc"><a href="c-chrono-time_t.html">time_t</a></span> 对象则返回 <span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">-</span><span class="nu0">1</span></span></span> （ POSIX 亦要求此情况下存储 <code>EOVERFLOW</code> 于 <span class="t-lc"><a href="c-error-errno.html">errno</a></span> 中）。</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>若 <span class="t-lc"><a href="c-chrono-tm.html">struct tm</a></span> 对象是由 POSIX <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/009695399/functions/strptime.html">strptime</a> 或等价的函数取得的，则 <code>tm_isdst</code> 的值不确定，并需要在调用 <code>mktime</code> 前显式设置。</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 // 为 GCC 的 setenv</span>
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<span class="co2">#include <stdlib.h></span>
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<span class="co2">#include <stdio.h></span>
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<span class="co2">#include <time.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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setenv<span class="br0">(</span><span class="st0">"TZ"</span>, <span class="st0">"/usr/share/zoneinfo/America/New_York"</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// POSIX 限定</span>
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<span class="kw1">struct</span> <a href="c-chrono-tm.html"><span class="kw522">tm</span></a> <a href="c-chrono-tm.html"><span class="kw522">tm</span></a> <span class="sy1">=</span> <span class="sy2">*</span><a href="c-chrono-localtime.html"><span class="kw520">localtime</span></a><span class="br0">(</span><span class="sy3">&</span><span class="br0">(</span><a href="c-chrono-time_t.html"><span class="kw523">time_t</span></a><span class="br0">)</span><span class="br0">{</span><a href="c-chrono-time.html"><span class="kw513">time</span></a><span class="br0">(</span><a href="c-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span><span class="br0">}</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"Today is %s"</span>, <a href="c-chrono-asctime.html"><span class="kw515">asctime</span></a><span class="br0">(</span><span class="sy3">&</span><a href="c-chrono-tm.html"><span class="kw522">tm</span></a><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"(DST is %s)<span class="es1">\n</span>"</span>, <a href="c-chrono-tm.html"><span class="kw522">tm</span></a>.<span class="me1">tm_isdst</span> <span class="sy4">?</span> <span class="st0">"in effect"</span> <span class="sy4">:</span> <span class="st0">"not in effect"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-chrono-tm.html"><span class="kw522">tm</span></a>.<span class="me1">tm_mon</span> <span class="sy2">-</span><span class="sy1">=</span> <span class="nu0">100</span><span class="sy4">;</span> <span class="co1">// tm_mon 落在正常范围外</span>
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mktime<span class="br0">(</span><span class="sy3">&</span><a href="c-chrono-tm.html"><span class="kw522">tm</span></a><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// tm_dst 不被设为 -1 ；使用今日的 DST 状态</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"100 months ago was %s"</span>, <a href="c-chrono-asctime.html"><span class="kw515">asctime</span></a><span class="br0">(</span><span class="sy3">&</span><a href="c-chrono-tm.html"><span class="kw522">tm</span></a><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw850">printf</span></a><span class="br0">(</span><span class="st0">"(DST was %s)<span class="es1">\n</span>"</span>, <a href="c-chrono-tm.html"><span class="kw522">tm</span></a>.<span class="me1">tm_isdst</span> <span class="sy4">?</span> <span class="st0">"in effect"</span> <span class="sy4">:</span> <span class="st0">"not in effect"</span><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>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">Today is Fri Apr 22 11:53:36 2016
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(DST is in effect)
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100 months ago was Sat Dec 22 10:53:36 2007
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(DST was not in effect)</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-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>7.27.2.3 The mktime function (p: 390-391)</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>7.23.2.3 The mktime function (p: 340-341)</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>4.12.2.3 The mktime 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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<td>
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<div class="t-dsc-member-div">
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<div><a href="c-chrono-localtime.html"><span class="t-lines"><span>localtime</span><span>localtime_r</span><span>localtime_s</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c23">(C23)</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>将从纪元开始的时间转换成以本地时间表示的日历时间<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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</div>
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</body>
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