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<title>std::chrono::operator+, std::chrono::operator- (std::chrono::month)</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::chrono::</span>operator+, <span style="font-size:0.7em; line-height:130%">std::chrono::</span>operator- <span style="font-size:0.7em; line-height:130%">(std::chrono::month)</span></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>&lrm; | <a href="cpp-chrono-month.html">month</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span> operator<span class="sy2">+</span><span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="sy3">&amp;</span> m,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="sy3">&amp;</span> ms<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span> operator<span class="sy2">+</span><span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="sy3">&amp;</span> ms,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="sy3">&amp;</span> m<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span> operator<span class="sy2">-</span><span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="sy3">&amp;</span> m,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="sy3">&amp;</span> ms<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(3)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span> operator<span class="sy2">-</span><span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="sy3">&amp;</span> m1,<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="sy3">&amp;</span> m2<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(4)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div class="t-li1"><span class="t-li">1-2)</span> &#23558; <code>ms.count()</code> &#20010;&#26376;&#21152;&#21040; <code>m</code> &#12290;&#36890;&#36807;&#39318;&#20808;&#27714;&#20540; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">static_cast</span><span class="sy1">&lt;</span><span class="kw4">long</span> <span class="kw4">long</span><span class="sy1">&gt;</span><span class="br0">(</span><span class="kw4">unsigned</span><span class="br0">(</span>m<span class="br0">)</span><span class="br0">)</span> <span class="sy2">+</span> <span class="br0">(</span>ms.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span></span></span> &#65292;&#23558;&#23427;&#23545; 12 &#21462;&#20313;&#21464;&#25104; [0, 11] &#33539;&#22260;&#20013;&#30340;&#25972;&#25968;&#65292;&#20877;&#21152; 1 &#65292;&#35745;&#31639;&#32467;&#26524;&#20013;&#20445;&#26377;&#30340;&#26376;&#20221;&#20540;&#12290;</div>
<div class="t-li1"><span class="t-li">3)</span> &#20174; <code>m</code> &#20943;&#21435; <code>ms.count()</code> &#20010;&#26376;&#24182;&#36820;&#22238;&#32467;&#26524;&#12290;&#31561;&#20215;&#20110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> m <span class="sy2">+</span> <span class="sy2">-</span>ms<span class="sy4">;</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">4)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp">m1.<span class="me1">ok</span><span class="br0">(</span><span class="br0">)</span></span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">m2.<span class="me1">ok</span><span class="br0">(</span><span class="br0">)</span></span></span> &#22343;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65292;&#21017;&#36820;&#22238; <span class="t-lc">std::chrono::months</span> &#20540; <code>m</code> &#65292;&#20351;&#24471; <code>m.count()</code> &#22312;&#33539;&#22260; [0, 11] &#20013;&#19988; <span class="t-c"><span class="mw-geshi cpp source-cpp">m2 <span class="sy2">+</span> m <span class="sy1">==</span> m1</span></span> &#12290;&#21542;&#21017;&#36820;&#22238;&#20540;&#26410;&#25351;&#23450;&#12290;</div>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<div class="t-li1"><span class="t-li">1-3)</span> &#20445;&#26377;&#25353;&#19978;&#36848;&#26041;&#24335;&#35745;&#31639;&#30340;&#26376;&#20221;&#20540;&#30340; <span class="t-lc">std::chrono::month</span> &#12290;</div>
<div class="t-li1"><span class="t-li">4)</span> &#34920;&#31034; <code>m1</code> &#19982; <code>m2</code> &#38388;&#36317;&#31163;&#30340; <span class="t-lc">std::chrono::months</span> &#12290;</div>
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">&#27880;&#24847;</span></h3>
<p>&#21482;&#35201;&#35745;&#31639;&#19981;&#28322;&#20986;&#65292; <span class="t-v">(1-3)</span> &#23601;&#22987;&#32456;&#36820;&#22238;&#21512;&#27861;&#30340;&#26376;&#20221;&#65292;&#21363;&#20351; <span class="t-c"><span class="mw-geshi cpp source-cpp">m.<span class="me1">ok</span><span class="br0">(</span><span class="br0">)</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</p>
<p>&#20108;&#20010; <code>month</code> &#20540;&#30456;&#20943;&#30340;&#32467;&#26524;&#26159; <span class="t-lc">std::chrono::months</span> &#31867;&#22411;&#30340;&#26102;&#38271;&#12290;&#26102;&#38271;&#21333;&#20301;&#34920;&#31034;&#26684;&#37324;&#39640;&#21033;&#26376;&#30340;&#24179;&#22343;&#38271;&#24230;&#65292;&#32780;&#20135;&#29983;&#30340;&#26102;&#38271;&#19982;&#36816;&#31639;&#25968;&#25152;&#34920;&#31034;&#30340;&#20855;&#20307;&#26376;&#20998;&#30340;&#26085;&#25968;&#26080;&#20851;&#12290;&#20363;&#22914; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-chrono-duration.html"><span class="kw997">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">seconds</span></span></a><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">April</span> <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">March</span><span class="br0">)</span></span></span> &#19981;&#26159;&#19977;&#26376;&#20013;&#30340;&#31186;&#25968; (<span class="t-c"><span class="mw-geshi cpp source-cpp">2678400s</span></span>) &#65292;&#32780;&#26159; <span class="t-c"><span class="mw-geshi cpp source-cpp">2629746s</span></span> (30.436875 days) &#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;cassert&gt;</span>
<span class="co2">#include &lt;chrono&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span> m <span class="br0">{</span><span class="nu0">6</span><span class="br0">}</span><span class="sy4">;</span>
m <span class="sy1">=</span> m <span class="sy2">+</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="br0">(</span><span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>m <span class="sy1">==</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="br0">(</span><span class="nu0">8</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
m <span class="sy1">=</span> m <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="br0">(</span><span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>m <span class="sy1">==</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="br0">(</span><span class="nu0">5</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span> ms <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="br0">(</span><span class="nu0">8</span><span class="br0">)</span> <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">month</span><span class="br0">(</span><span class="nu0">6</span><span class="br0">)</span><span class="sy4">;</span>
static_assert<span class="br0">(</span>ms <span class="sy1">==</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">months</span><span class="br0">(</span><span class="nu0">2</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-chrono-month-operator_inc_dec.html"><span class="t-lines"><span>operator++</span><span>operator++<span class="t-dsc-small">(int)</span></span><span>operator--</span><span>operator--<span class="t-dsc-small">(int)</span></span></span></a></div>
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<td>&#33258;&#22686;&#25110;&#33258;&#20943; month<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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<div class="t-dsc-member-div">
<div><a href="cpp-chrono-month-operator_arith.html"><span class="t-lines"><span>operator+=</span><span>operator-=</span></span></a></div>
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<td>&#21152;&#25110;&#20943;&#26376;&#25968;<br />
<span class="t-mark">(&#20844;&#24320;&#25104;&#21592;&#20989;&#25968;)</span></td>
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