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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::chrono::</span>is_clock</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-chrono.html">chrono</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-chrono.html">&lt;chrono&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span><br />
<span class="kw1">struct</span> is_clock<span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<p>&#33509; <code>T</code> &#28385;&#36275;<a href="cpp-named_req-Clock.html"><span style="font-style:italic">&#26102;&#38047;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Clock)</span></a> &#35201;&#27714;&#65292;&#21017;&#25552;&#20379;&#31561;&#20110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#30340;&#25104;&#21592;&#24120;&#37327; <code>value</code> &#65292;&#23545;&#20110;&#20219;&#20309;&#20854;&#20182;&#31867;&#22411;&#65292; <code>value</code> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</p>
<p>&#20026;&#27492;&#29305;&#24615;&#30340;&#30446;&#30340;&#65292;&#23454;&#29616;&#30830;&#23450;&#31867;&#22411;&#19981;&#33021;&#28385;&#36275;<a href="cpp-named_req-Clock.html"><span style="font-style:italic">&#26102;&#38047;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Clock)</span></a> &#35201;&#27714;&#30340;&#22806;&#24310;&#26159;&#26410;&#25351;&#23450;&#30340;&#65292;&#38500;&#20102;&#33267;&#23569; <code>T</code> &#19981;&#24212;&#24403;&#20855;&#22791;<a href="cpp-named_req-Clock.html"><span style="font-style:italic">&#26102;&#38047;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Clock)</span></a> &#30340;&#36164;&#26684;&#65292;&#38500;&#38750;&#23427;&#28385;&#36275;&#25152;&#26377;&#19979;&#21015;&#26465;&#20214;&#65306;</p>
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<li><i>qualified-id</i> <code>T::rep</code> &#12289; <code>T::period</code> &#12289; <code>T::duration</code> &#21644; <code>T::time_point</code> &#22343;&#21512;&#27861;&#24182;&#19988;&#27599;&#20010;&#37117;&#20195;&#34920;&#19968;&#20010;&#31867;&#22411;&#65307;</li>
<li>&#34920;&#36798;&#24335; <code>T::is_steady</code> &#21644; <code>T::now()</code> &#22312;&#24403;&#20570;&#19981;&#27714;&#20540;&#36816;&#31639;&#25968;&#26102;&#22343;&#20026;&#33391;&#26500;&#12290;</li>
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<p>&#28155;&#21152; <code>is_clock</code> &#25110; <code>is_clock_v</code> &#30340;&#29305;&#21270;&#30340;&#31243;&#24207;&#34892;&#20026;&#26410;&#23450;&#20041;&#12290;</p>
<h3><span class="mw-headline" id=".E6.A8.A1.E6.9D.BF.E5.BD.A2.E5.8F.82">&#27169;&#26495;&#24418;&#21442;</span></h3>
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<td>T</td>
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<h3><span class="mw-headline" id=".E8.BE.85.E5.8A.A9.E5.8F.98.E9.87.8F.E6.A8.A1.E6.9D.BF">&#36741;&#21161;&#21464;&#37327;&#27169;&#26495;</span></h3>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T <span class="sy1">&gt;</span><br />
<span class="kw1">inline</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> is_clock_v <span class="sy1">=</span> is_clock<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy4">::</span><span class="me2">value</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<h2><span class="mw-headline" id=".E7.BB.A7.E6.89.BF.E8.87.AA_std::integral_constant">&#32487;&#25215;&#33258; <a href="cpp-types-integral_constant.html"><span style="font-size:0.7em; line-height:130%">std::</span>integral_constant</a></span></h2>
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">&#25104;&#21592;&#24120;&#37327;</span></h3>
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<div><span class="t-lines"><span>value</span></span></div>
<div><span class="t-lines"><span><span class="t-cmark">[&#38745;&#24577;]</span></span></span></div>
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<td>&#33509; <code>T</code> &#28385;&#36275;<a href="cpp-named_req-Clock.html"><span style="font-style:italic">&#26102;&#38047;</span> <span style="font-family: Georgia, &#39;DejaVu Serif&#39;, serif; font-style:italic">(Clock)</span></a> &#35201;&#27714;&#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65292;&#21542;&#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span><br />
<span class="t-mark">(&#20844;&#24320;&#38745;&#24577;&#25104;&#21592;&#24120;&#37327;)</span></td>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">&#25104;&#21592;&#20989;&#25968;</span></h3>
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<div><span class="t-lines"><span>operator bool</span></span></div>
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<td>&#36716;&#25442;&#23545;&#35937;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> &#65292;&#36820;&#22238; <code>value</code><br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div><span class="t-lines"><span>operator()</span></span></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div>
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<td>&#36820;&#22238; <code>value</code><br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">&#25104;&#21592;&#31867;&#22411;</span></h3>
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<td><code>value_type</code></td>
<td><code>bool</code></td>
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<td><code>type</code></td>
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-integral_constant.html"><span class="kw647">std::<span class="me2">integral_constant</span></span></a><span class="sy1">&lt;</span><span class="kw4">bool</span>, value<span class="sy1">&gt;</span></span></span></td>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">&#21487;&#33021;&#30340;&#23454;&#29616;</span></h3>
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<pre class="de1"><span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span><span class="sy1">&gt;</span>
<span class="kw1">struct</span> is_clock <span class="sy4">:</span> <a href="cpp-types-integral_constant.html"><span class="kw650">std::<span class="me2">false_type</span></span></a> <span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">class</span> T<span class="sy1">&gt;</span>
requires
requires <span class="br0">{</span>
<span class="kw1">typename</span> T<span class="sy4">::</span><span class="me2">rep</span><span class="sy4">;</span>
<span class="kw1">typename</span> T<span class="sy4">::</span><span class="me2">period</span><span class="sy4">;</span>
<span class="kw1">typename</span> T<span class="sy4">::</span><span class="me2">duration</span><span class="sy4">;</span>
<span class="kw1">typename</span> T<span class="sy4">::</span><span class="me2">time_point</span><span class="sy4">;</span>
T<span class="sy4">::</span><span class="me2">is_steady</span><span class="sy4">;</span>
T<span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">struct</span> is_clock<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span> <span class="sy4">:</span> <a href="cpp-types-integral_constant.html"><span class="kw649">std::<span class="me2">true_type</span></span></a> <span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
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