76 lines
8.1 KiB
HTML
76 lines
8.1 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>C++ 具名要求：时钟 (Clock)</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_named_req_Clock skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">C++ 具名要求：</span><span style="font-style:italic">时钟</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Clock)</span></h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-named_req.html">named req</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<p><strong class="selflink"><span style="font-style:italic">时钟</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Clock)</span></strong> 要求描述由 <span class="t-lc"><a href="cpp-chrono-duration.html">std::chrono::duration</a></span> 、 <span class="t-lc"><a href="cpp-chrono-time_point.html">std::chrono::time_point</a></span> 和获取当前 time_point 的函数 <span class="t-c"><span class="mw-geshi cpp source-cpp">now<span class="br0">(</span><span class="br0">)</span></span></span> 组成的一束内容。时钟的纪元指代时钟的 time_point 的原点。</p>
|
|
<h3><span class="mw-headline" id=".E8.A6.81.E6.B1.82">要求</span></h3>
|
|
<p><span class="t-c"><span class="mw-geshi cpp source-cpp">C1</span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp">C2</span></span> 表示时钟类型。 <span class="t-c"><span class="mw-geshi cpp source-cpp">t1</span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp">t2</span></span> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span></span></span> 返回的值，其中返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">t1</span></span> 的调用先发生于返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">t2</span></span> 的调用，且两者都先发生于 <span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">time_point</span><span class="sy4">::</span><span class="me2">max</span><span class="br0">(</span><span class="br0">)</span></span></span> 。</p>
|
|
<table class="wikitable">
|
|
<tr>
|
|
<th>表达式</th>
|
|
<th>返回类型</th>
|
|
<th>操作语义</th>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">rep</span></span></span></td>
|
|
<td>算术类型或模拟算术类型的类</td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">duration</span></span></span> 的表示类型。</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">period</span></span></span></td>
|
|
<td><span class="t-lc"><a href="cpp-numeric-ratio-ratio.html">std::ratio</a></span> 的特化</td>
|
|
<td>时钟的每秒计次周期。</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">duration</span></span></span></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-chrono-duration.html"><span class="kw993">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">duration</span></span></a><span class="sy1"><</span>C1<span class="sy4">::</span><span class="me2">rep</span>, C1<span class="sy4">::</span><span class="me2">period</span><span class="sy1">></span></span></span></td>
|
|
<td>时钟的时期类型。</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">time_point</span></span></span></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-chrono-time_point.html"><span class="kw991">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">time_point</span></span></a><span class="sy1"><</span>C1<span class="sy1">></span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-chrono-time_point.html"><span class="kw991">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">time_point</span></span></a><span class="sy1"><</span>C2, C1<span class="sy4">::</span><span class="me2">duration</span><span class="sy1">></span></span></span></td>
|
|
<td>时钟的 <span class="t-lc"><a href="cpp-chrono-time_point.html">std::chrono::time_point</a></span> 类型。 C1 与 C2 应指同一纪元。</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">is_steady</span></span></span></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="kw4">bool</span></span></span></td>
|
|
<td>若 <span class="t-c"><span class="mw-geshi cpp source-cpp">t1 <span class="sy1"><=</span> t2</span></span> 始终为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 且时钟计次之间的时间间隔为常量，则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span></td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span></span></span></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">C1<span class="sy4">::</span><span class="me2">time_point</span></span></span></td>
|
|
<td>返回表示时间中当前点的 <span class="t-c"><span class="mw-geshi cpp source-cpp">time_point</span></span> 对象。</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-chrono-is_clock.html"><span class="t-lines"><span>is_clock</span><span>is_clock_v</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>确定类型是否为<strong class="selflink"><span style="font-style:italic">时钟</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Clock)</span></strong><br />
|
|
<span class="t-mark">(类模板)</span> <span class="t-mark">(变量模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|