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<title>operator==, !=, &lt;, &lt;=, &gt;, &gt;=, &lt;=&gt;(std::optional)</title>
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<h1 id="firstHeading" class="firstHeading">operator==, !=, &lt;, &lt;=, &gt;, &gt;=, &lt;=&gt;<span style="font-size:0.7em; line-height:130%">(std::optional)</span></h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-utility.html">utility</a>&lrm; | <a href="cpp-utility-optional.html">optional</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-optional.html">&lt;optional&gt;</a></code></div>
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<div>&#27604;&#36739;&#20108;&#20010; <code>optional</code> &#23545;&#35937;</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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(3)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(4)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<tr class="t-dcl t-since-cxx17">
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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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(5)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<tr class="t-dcl t-since-cxx17">
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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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(6)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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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, std<span class="sy4">::</span><span class="me2">three_way_comparable_with</span><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span> U <span class="sy1">&gt;</span><br /></span>
<p><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">compare_three_way_result_t</span><span class="sy1">&lt;</span>T, U<span class="sy1">&gt;</span><br /></p>
&nbsp; &nbsp; operator<span class="sy1">&lt;=&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> lhs, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> rhs <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(7)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<div>&#27604;&#36739;&#19968;&#20010; <code>optional</code> &#23545;&#35937;&#19982; <code>nullopt</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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(8)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
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<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(9)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(10)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(11)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(12)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(13)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(14)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;=</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(15)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(16)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(17)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(18)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17 t-until-cxx20">
<td>
<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="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;=</span><span class="br0">(</span> <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a>, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
</td>
<td>(19)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span><br />
<span class="t-mark-rev t-until-cxx20">(C++20 &#21069;)</span></td>
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<td>
<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>
<p><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">strong_ordering</span><br /></p>
&nbsp; &nbsp; operator<span class="sy1">&lt;=&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <a href="cpp-utility-optional-nullopt_t.html"><span class="kw1078">std::<span class="me2">nullopt_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
</td>
<td>(20)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<tr class="t-dcl-h">
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<div>&#27604;&#36739;&#19968;&#20010; <code>optional</code> &#23545;&#35937;&#19982;&#19968;&#20010; <code>T</code></div>
</td>
<td></td>
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<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value<span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(21)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(22)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(23)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(24)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(25)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(26)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(27)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&lt;=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt<span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(28)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(29)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(30)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;=</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(31)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx17">
<td>
<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="kw1">class</span> U <span class="sy1">&gt;</span><br />
<span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">&gt;=</span><span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&amp;</span> value, <span class="kw4">const</span> optional<span class="sy1">&lt;</span>U<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt <span class="br0">)</span><span class="sy4">;</span></span></div>
</td>
<td>(32)</td>
<td><span class="t-mark-rev t-since-cxx17">(C++17 &#36215;)</span></td>
</tr>
<tr class="t-dcl t-since-cxx20">
<td>
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> T, std<span class="sy4">::</span><span class="me2">three_way_comparable_with</span><span class="sy1">&lt;</span>T<span class="sy1">&gt;</span> U <span class="sy1">&gt;</span><br /></span>
<p><span class="kw4">constexpr</span> std<span class="sy4">::</span><span class="me2">compare_three_way_result_t</span><span class="sy1">&lt;</span>T, U<span class="sy1">&gt;</span><br /></p>
&nbsp; &nbsp; operator<span class="sy1">&lt;=&gt;</span><span class="br0">(</span> <span class="kw4">const</span> optional<span class="sy1">&lt;</span>T<span class="sy1">&gt;</span><span class="sy3">&amp;</span> opt, <span class="kw4">const</span> U<span class="sy3">&amp;</span> value <span class="br0">)</span><span class="sy4">;</span></div>
</td>
<td>(33)</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
</tr>
<tr class="t-dcl-sep">
<td></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
<p>&#36827;&#34892; <code>optional</code> &#23545;&#35937;&#19978;&#30340;&#27604;&#36739;&#12290;</p>
<div class="t-li1"><span class="t-li">1-7)</span> &#27604;&#36739;&#20108;&#20010; <code>optional</code> &#23545;&#35937;&#65292; <code>lhs</code> &#21644; <code>rhs</code> &#12290;&#20165;&#33509; <code>lhs</code> &#19982; <code>rhs</code> &#37117;&#21547;&#20540;&#65292;&#25165;&#27604;&#36739;&#23481;&#32435;&#30340;&#20540;&#65288;&#20351;&#29992; <code>T</code> &#23545;&#24212;&#30340;&#36816;&#31639;&#31526;&#65289;&#12290;&#21542;&#21017;&#65292;</div>
<dl>
<dd>
<dl>
<dd>
<ul>
<li>&#33509;&#19988;&#21807;&#33509; <code>lhs</code> &#19982; <code>rhs</code> &#37117;&#19981;&#21547;&#20540;&#65292;&#25165;&#35748;&#20026; <code>lhs</code> <i>&#31561;&#20110;</i> <code>rhs</code> &#12290;</li>
<li>&#33509;&#19988;&#21807;&#33509; <code>rhs</code> &#21547;&#20540;&#19988; <code>lhs</code> &#19981;&#21547;&#20540;&#65292;&#25165;&#35748;&#20026; <code>lhs</code> <i>&#23567;&#20110;</i> <code>rhs</code> &#12290;</li>
</ul>
</dd>
</dl>
</dd>
</dl>
<div class="t-li1"><span class="t-li">8-20)</span> &#27604;&#36739; <code>opt</code> &#19982; <code>nullopt</code> &#27604;&#36739;&#12290;&#19982; (1-6) &#20013;&#19982;&#19981;&#21547;&#20540;&#30340; <code>optional</code> &#27604;&#36739;&#26102;&#31561;&#20215;&#12290;
<table class="t-rev-begin">
<tr class="t-rev t-since-cxx20">
<td>
<p><code>&lt;</code>&#12289; <code>&lt;=</code>&#12289; <code>&gt;</code>&#12289; <code>&gt;=</code> &#21450; <code>!=</code> &#36816;&#31639;&#31526;&#20998;&#21035;&#20174; <code>operator&lt;=&gt;</code> &#19982; <code>operator==</code> <a href="cpp-language-operators.html#.E5.85.B3.E7.B3.BB.E8.BF.90.E7.AE.97.E7.AC.A6">&#21512;&#25104;</a>&#12290;</p>
</td>
<td><span class="t-mark-rev t-since-cxx20">(C++20 &#36215;)</span></td>
</tr>
</table>
</div>
<div class="t-li1"><span class="t-li">21-33)</span> &#27604;&#36739; <code>opt</code> &#19982;<code>value</code> &#12290;&#20165;&#33509; <code>opt</code> &#21547;&#20540;&#25165;&#27604;&#36739;&#20540;&#12290;&#21542;&#21017;&#35748;&#20026; <code>opt</code> <i>&#23567;&#20110;</i> <code>value</code> &#12290;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>opt</span></span> &#19982; <span class="t-c"><span class="mw-geshi cpp source-cpp">value</span></span> &#38388;&#30340;&#23545;&#24212;&#21452;&#36335;&#27604;&#36739;&#34920;&#36798;&#24335;&#38750;&#33391;&#26500;&#65292;&#25110;&#33509;&#32467;&#26524;&#19981;&#33021;&#36716;&#25442;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> &#65292;&#21017;&#31243;&#24207;&#38750;&#33391;&#26500;&#12290;</div>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td>lhs, rhs, opt</td>
<td>-</td>
<td>&#35201;&#27604;&#36739;&#30340; <code>optional</code> &#23545;&#35937;</td>
</tr>
<tr class="t-par">
<td>value</td>
<td>-</td>
<td>&#19982;&#25152;&#21547;&#20540;&#27604;&#36739;&#30340;&#20540;</td>
</tr>
</table>
<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)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> <span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65288;&#19988; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#20134;&#28982;&#65289;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy1">==</span> <span class="sy2">*</span>rhs</span></span>&#12290;</div>
<div class="t-li1"><span class="t-li">2)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> <span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65288;&#19988; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#20134;&#28982;&#65289;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy3">!</span><span class="sy1">=</span> <span class="sy2">*</span>rhs</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">3)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy1">&lt;</span> <span class="sy2">*</span>rhs</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"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy1">&lt;=</span> <span class="sy2">*</span>rhs</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">5)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy1">&gt;</span> <span class="sy2">*</span>rhs</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">6)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65307;<br />
<p>&#21542;&#21017;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> &#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#65307;<br /></p>
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>lhs <span class="sy1">&gt;=</span> <span class="sy2">*</span>rhs</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">7)</span> &#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy3">&amp;&amp;</span> <span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#21017;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>x <span class="sy1">&lt;=&gt;</span> <span class="sy2">*</span>y</span></span> &#65307;<br />
&#21542;&#21017;&#65292;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>lhs<span class="br0">)</span> <span class="sy1">&lt;=&gt;</span> <span class="kw4">bool</span><span class="br0">(</span>rhs<span class="br0">)</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">8-9)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>opt</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">10-11)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">12)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">13)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">14)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>opt</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">15)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">16)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">17)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">18)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">19)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>opt</span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">20)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy1">&lt;=&gt;</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">21)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">==</span> value <span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">22)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy1">==</span> <span class="sy2">*</span>opt <span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">23)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy3">!</span><span class="sy1">=</span> value <span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">24)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy3">!</span><span class="sy1">=</span> <span class="sy2">*</span>opt <span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">25)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">&lt;</span> value &nbsp;<span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">26)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy1">&lt;</span> <span class="sy2">*</span>opt &nbsp;<span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">27)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">&lt;=</span> value <span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">28)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy1">&lt;=</span> <span class="sy2">*</span>opt <span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">29)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">&gt;</span> value &nbsp;<span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">30)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy1">&gt;</span> <span class="sy2">*</span>opt &nbsp;<span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">31)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">&gt;=</span> value <span class="sy4">:</span> <span class="kw2">false</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">32)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> value <span class="sy1">&gt;=</span> <span class="sy2">*</span>opt <span class="sy4">:</span> <span class="kw2">true</span></span></span> &#12290;</div>
<div class="t-li1"><span class="t-li">33)</span> &#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>opt<span class="br0">)</span> <span class="sy4">?</span> <span class="sy2">*</span>opt <span class="sy1">&lt;=&gt;</span> value <span class="sy4">:</span> std<span class="sy4">::</span><span class="me2">strong_ordering</span><span class="sy4">::</span><span class="me2">less</span></span></span> &#12290;</div>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<div class="t-li1"><span class="t-li">1-7)</span> &#21487;&#33021;&#25243;&#20986;&#23454;&#29616;&#23450;&#20041;&#30340;&#24322;&#24120;&#12290;</div>
<div class="t-li1"><span class="t-li">21-33)</span> &#22312;&#27604;&#36739;&#25243;&#20986;&#26102;&#25243;&#20986;&#20854;&#25152;&#25243;&#20986;&#30340;&#24322;&#24120;&#12290;</div>
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">&#32570;&#38519;&#25253;&#21578;</span></h3>
<p>&#19979;&#21015;&#26356;&#25913;&#34892;&#20026;&#30340;&#32570;&#38519;&#25253;&#21578;&#36861;&#28335;&#22320;&#24212;&#29992;&#20110;&#20197;&#21069;&#20986;&#29256;&#30340; C++ &#26631;&#20934;&#12290;</p>
<table class="dsctable" style="font-size:0.8em">
<tr>
<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
</tr>
<tr>
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2945">LWG 2945</a></td>
<td>C++17</td>
<td>&ldquo;&#19982; T &#27604;&#36739;&rdquo;&#24773;&#20917;&#30340;&#27169;&#26495;&#24418;&#21442;&#39034;&#24207;&#19981;&#19968;&#33268;</td>
<td>&#20351;&#20043;&#19968;&#33268;</td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
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