329 lines
33 KiB
HTML
329 lines
33 KiB
HTML
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<title>operator==, !=, <, <=, >, >=, <=> (std::shared_ptr)</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_memory_shared_ptr_operator_cmp skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading">operator==, !=, <, <=, >, >=, <=> <small>(std::shared_ptr)</small></h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-memory.html">memory</a>‎ | <a href="cpp-memory-shared_ptr.html">shared ptr</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-memory.html"><memory></a></code></div>
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<div>比较二个 <code>shared_ptr</code> 对象</div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy1"><</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy1">></span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy1"><=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="sy1">>=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(6)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p>std<span class="sy4">::</span><span class="me2">strong_ordering</span> operator<span class="sy1"><=></span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(7)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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<div>比较 <code>shared_ptr</code> 与空指针</div>
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</td>
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<td></td>
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<td></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(8)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(9)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(10)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(11)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1"><</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(12)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1"><</span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(13)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">></span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(14)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">></span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(15)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1"><=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(16)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1"><=</span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(17)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">>=</span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs, <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(18)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11 t-until-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw4">bool</span> operator<span class="sy1">>=</span><span class="br0">(</span> <a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a>, <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(19)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br /></span>
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<p>std<span class="sy4">::</span><span class="me2">strong_ordering</span> operator<span class="sy1"><=></span><span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> lhs,<br /></p>
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<a href="cpp-types-nullptr_t.html"><span class="kw102">std::<span class="me2">nullptr_t</span></span></a> <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
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</td>
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<td>(20)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>比较二个 <code>shared_ptr<T></code> 对象或将 <code>shared_ptr<T></code> 与空指针比较。</p>
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<p>注意 <code>shared_ptr</code> 的比较运算符简单地比较指针值；<i>不</i>比较所指向的实际对象。对 <code>shared_ptr</code> 定义 <code>operator<</code> 允许将 <code>shared_ptr</code> 用作关联容器，如 <span class="t-lc"><a href="cpp-container-map.html">std::map</a></span> 与 <span class="t-lc"><a href="cpp-container-set.html">std::set</a></span> 中的键。</p>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx20">
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<td>
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<p><code><</code>、 <code><=</code>、 <code>></code>、 <code>>=</code> 及 <code>!=</code> 运算符分别从 <code>operator<=></code> 与 <code>operator==</code> <a href="cpp-language-operators.html#.E5.85.B3.E7.B3.BB.E8.BF.90.E7.AE.97.E7.AC.A6">合成</a>。</p>
|
|
</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
</table>
|
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
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<tr class="t-par">
|
|
<td>lhs</td>
|
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<td>-</td>
|
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<td>要比较的左侧 <code>shared_ptr</code></td>
|
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</tr>
|
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<tr class="t-par">
|
|
<td>rhs</td>
|
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<td>-</td>
|
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<td>要比较的右侧 <code>shared_ptr</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<div class="t-li1"><span class="t-li">1)</span> <code>lhs.get() == rhs.get()</code></div>
|
|
<div class="t-li1"><span class="t-li">2)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>lhs <span class="sy1">==</span> rhs<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">3)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-less.html"><span class="kw1039">std::<span class="me2">less</span></span></a><span class="sy1"><</span>V<span class="sy1">></span><span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>lhs.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span>, rhs.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> ，其中 V 是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span></span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span></span></span> 的<a href="cpp-language-operator_comparison.html#.E6.8C.87.E9.92.88.E6.AF.94.E8.BE.83.E8.BF.90.E7.AE.97.E7.AC.A6">合成指针类型</a></div>
|
|
<div class="t-li1"><span class="t-li">4)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">rhs <span class="sy1"><</span> lhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">5)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>rhs <span class="sy1"><</span> lhs<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">6)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>lhs <span class="sy1"><</span> rhs<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">7)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">compare_three_way</span><span class="br0">{</span><span class="br0">}</span><span class="br0">(</span>x.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span>, y.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">8)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>lhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">9)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>rhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">10)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span><span class="kw4">bool</span><span class="br0">)</span>lhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">11)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span><span class="kw4">bool</span><span class="br0">)</span>rhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">12)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-less.html"><span class="kw1039">std::<span class="me2">less</span></span></a><span class="sy1"><</span><a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>lhs.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span>, nullptr<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">13)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-less.html"><span class="kw1039">std::<span class="me2">less</span></span></a><span class="sy1"><</span><a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>nullptr, rhs.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">14)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">nullptr <span class="sy1"><</span> lhs</span></span></div>
|
|
<div class="t-li1"><span class="t-li">15)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">rhs <span class="sy1"><</span> nullptr</span></span></div>
|
|
<div class="t-li1"><span class="t-li">16)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>nullptr <span class="sy1"><</span> lhs<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">17)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>rhs <span class="sy1"><</span> nullptr<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">18)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>lhs <span class="sy1"><</span> nullptr<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">19)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span><span class="br0">(</span>nullptr <span class="sy1"><</span> rhs<span class="br0">)</span></span></span></div>
|
|
<div class="t-li1"><span class="t-li">20)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">compare_three_way</span><span class="br0">{</span><span class="br0">}</span><span class="br0">(</span>x.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span>, <span class="kw1">static_cast</span><span class="sy1"><</span><a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="sy4">::</span><span class="me2">element_type</span><span class="sy2">*</span><span class="sy1">></span><span class="br0">(</span>nullptr<span class="br0">)</span><span class="br0">)</span></span></span></div>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>所有情况下，被比较者是存储的指针（ <span class="t-lc"><a href="cpp-memory-shared_ptr-get.html">get()</a></span> 所返回者）而非被管理指针（ uses_count 达到零时传递给删除器者）。二个指针可能在用别名使用构造函数创建的 shared_ptr 中有别。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
|
|
<tr>
|
|
<td class="mbox-empty-cell"></td>
|
|
<td class="mbox-text" style="">本节未完成<br />
|
|
原因：暂无示例</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
|
<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
|
|
<table class="dsctable" style="font-size:0.8em">
|
|
<tr>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<th>出版时的行为</th>
|
|
<th>正确行为</th>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3427">LWG 3427</a></td>
|
|
<td>C++20</td>
|
|
<td><code>operator<=>(shared_ptr, nullptr_t)</code> 非良构</td>
|
|
<td>修正定义</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-memory-shared_ptr-get.html"><span class="t-lines"><span>get</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>返回存储的指针<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
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</body>
|
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</html>
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