91 lines
6.5 KiB
HTML
91 lines
6.5 KiB
HTML
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<title>std::chrono::time_point<Clock,Duration>::min</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::chrono::time_point<Clock,Duration>::</span>min</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-chrono.html">chrono</a>‎ | <a href="cpp-chrono-time_point.html">time point</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> <span class="kw4">constexpr</span> time_point min<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> <span class="kw4">constexpr</span> time_point min<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p>返回拥有最小可能时长的 <code>time_point</code> ,即 <span class="t-c"><span class="mw-geshi cpp source-cpp">time_point<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">duration</span><span class="sy4">::</span><span class="me2">min</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> 。</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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<p>(无)</p>
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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>最小的可能的 <code>time_point</code></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 <ratio></span>
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<span class="co2">#include <chrono></span>
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<span class="kw4">constexpr</span> <span class="kw4">auto</span> steady_min <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">steady_clock</span><span class="sy4">::</span><span class="me2">time_point</span><span class="sy4">::</span><span class="me2">min</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</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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<span class="kw4">auto</span> last_frame <span class="sy1">=</span> steady_min<span class="sy4">;</span>
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<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><span class="kw4">float</span>, <a href="cpp-numeric-ratio-ratio.html"><span class="kw1528">std::<span class="me2">milli</span></span></a><span class="sy1">></span> game_time <span class="br0">{</span><span class="nu17">0.0F</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> count <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> count <span class="sy1"><</span> <span class="nu0">5</span><span class="sy4">;</span> <span class="sy2">++</span>count<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw4">auto</span> current_frame <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">steady_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 若是首帧则初始化计时器:</span>
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<span class="kw1">if</span> <span class="br0">(</span>last_frame <span class="sy1">==</span> steady_min<span class="br0">)</span>
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last_frame <span class="sy1">=</span> current_frame<span class="sy4">;</span>
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game_time <span class="sy2">+</span><span class="sy1">=</span> current_frame <span class="sy2">-</span> last_frame<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">"Drawing frame at "</span> <span class="sy1"><<</span> game_time.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" ms<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="co1">// 在时间偏移 game_time 绘制帧……</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">Drawing frame at 0 ms
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Drawing frame at 0.17551 ms
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Drawing frame at 0.358325 ms
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Drawing frame at 0.545384 ms
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Drawing frame at 0.736717 ms</pre></div>
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