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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::weak_ptr&lt;T&gt;::</span>owner_before</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-memory.html">memory</a>&lrm; | <a href="cpp-memory-weak_ptr.html">weak ptr</a></span></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> Y <span class="sy1">&gt;</span><br />
<span class="kw4">bool</span> owner_before<span class="br0">(</span> <span class="kw4">const</span> weak_ptr<span class="sy1">&lt;</span>Y<span class="sy1">&gt;</span><span class="sy3">&amp;</span> other<span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></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> Y <span class="sy1">&gt;</span><br />
<span class="kw4">bool</span> owner_before<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">&lt;</span>Y<span class="sy1">&gt;</span><span class="sy3">&amp;</span> other<span class="br0">)</span> <span class="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<p>&#20197;&#23454;&#29616;&#23450;&#20041;&#30340;&#22522;&#20110;&#25317;&#26377;&#32773;&#65288;&#19982;&#22522;&#20110;&#20540;&#30456;&#21453;&#65289;&#39034;&#24207;&#65292;&#26816;&#26597;&#27492; <code>weak_ptr</code> &#26159;&#21542;&#20808;&#20110; <code>other</code> &#12290;&#20108;&#20010;&#26234;&#33021;&#25351;&#38024;&#20165;&#33509;&#37117;&#21344;&#26377;&#21516;&#19968;&#23545;&#35937;&#25110;&#22343;&#20026;&#31354;&#25165;&#27604;&#36739;&#30456;&#31561;&#65292;&#21363;&#20351;&#30001; get() &#33719;&#24471;&#30340;&#25351;&#38024;&#19981;&#21516;&#65288;&#20363;&#22914;&#22240;&#20026;&#23427;&#20204;&#25351;&#21521;&#21516;&#19968;&#23545;&#35937;&#20013;&#30340;&#19981;&#21516;&#23376;&#23545;&#35937;&#65289;&#12290;</p>
<p>&#27492;&#39034;&#24207;&#29992;&#20110;&#20196;&#20849;&#20139;&#21644;&#24369;&#25351;&#38024;&#21487;&#29992;&#20316;&#20851;&#32852;&#23481;&#22120;&#20013;&#30340;&#20851;&#38190;&#65292;&#36890;&#24120;&#32463;&#30001; <span class="t-lc"><a href="cpp-memory-owner_less.html">std::owner_less</a></span> &#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>other</td>
<td>-</td>
<td>&#35201;&#27604;&#36739;&#30340; <span class="t-lc"><a href="cpp-memory-shared_ptr.html">std::shared_ptr</a></span> &#25110; <span class="t-lc"><a href="cpp-memory-weak_ptr.html">std::weak_ptr</a></span></td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> &#21069;&#20110; <code>other</code> &#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65292;&#21542;&#21017;&#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;&#24120;&#35265;&#23454;&#29616;&#27604;&#36739;&#25511;&#21046;&#22359;&#30340;&#22320;&#22336;&#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;iostream&gt;</span>
<span class="co2">#include &lt;memory&gt;</span>
<span class="kw1">struct</span> Foo <span class="br0">{</span>
<span class="kw4">int</span> n1<span class="sy4">;</span>
<span class="kw4">int</span> n2<span class="sy4">;</span>
Foo<span class="br0">(</span><span class="kw4">int</span> a, <span class="kw4">int</span> b<span class="br0">)</span> <span class="sy4">:</span> n1<span class="br0">(</span>a<span class="br0">)</span>, n2<span class="br0">(</span>b<span class="br0">)</span> <span class="br0">{</span><span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">auto</span> p1 <span class="sy1">=</span> <a href="cpp-memory-shared_ptr-make_shared.html"><span class="kw736">std::<span class="me2">make_shared</span></span></a><span class="sy1">&lt;</span>Foo<span class="sy1">&gt;</span><span class="br0">(</span><span class="nu0">1</span>, <span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p2<span class="br0">(</span>p1, <span class="sy3">&amp;</span>p1<span class="sy2">-</span><span class="sy1">&gt;</span>n1<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-memory-shared_ptr.html"><span class="kw734">std::<span class="me2">shared_ptr</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> p3<span class="br0">(</span>p1, <span class="sy3">&amp;</span>p1<span class="sy2">-</span><span class="sy1">&gt;</span>n2<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1764">std::<span class="me2">boolalpha</span></span></a>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;p2 &lt; p3 &quot;</span> <span class="sy1">&lt;&lt;</span> <span class="br0">(</span>p2 <span class="sy1">&lt;</span> p3<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;p3 &lt; p2 &quot;</span> <span class="sy1">&lt;&lt;</span> <span class="br0">(</span>p3 <span class="sy1">&lt;</span> p2<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;p2.owner_before(p3) &quot;</span> <span class="sy1">&lt;&lt;</span> p2.<span class="me1">owner_before</span><span class="br0">(</span>p3<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;p3.owner_before(p2) &quot;</span> <span class="sy1">&lt;&lt;</span> p3.<span class="me1">owner_before</span><span class="br0">(</span>p2<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-memory-weak_ptr.html"><span class="kw741">std::<span class="me2">weak_ptr</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> w2<span class="br0">(</span>p2<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-memory-weak_ptr.html"><span class="kw741">std::<span class="me2">weak_ptr</span></span></a><span class="sy1">&lt;</span><span class="kw4">int</span><span class="sy1">&gt;</span> w3<span class="br0">(</span>p3<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>
<span class="co1">// &lt;&lt; &quot;w2 &lt; w3 &quot; &lt;&lt; (w2 &lt; w3) &lt;&lt; &#39;\n&#39; // won&#39;t compile </span>
<span class="co1">// &lt;&lt; &quot;w3 &lt; w2 &quot; &lt;&lt; (w3 &lt; w2) &lt;&lt; &#39;\n&#39; // won&#39;t compile</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;w2.owner_before(w3) &quot;</span> <span class="sy1">&lt;&lt;</span> w2.<span class="me1">owner_before</span><span class="br0">(</span>w3<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;w3.owner_before(w2) &quot;</span> <span class="sy1">&lt;&lt;</span> w3.<span class="me1">owner_before</span><span class="br0">(</span>w2<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">p2 &lt; p3 true
p3 &lt; p2 false
p2.owner_before(p3) false
p3.owner_before(p2) false
w2.owner_before(w3) false
w3.owner_before(w2) false</pre></div>
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<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>
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<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2873">LWG 2873</a></td>
<td>C++11</td>
<td><code>owner_before</code> &#21487;&#20197;&#19981;&#22768;&#26126;&#20026; noexcept</td>
<td>&#22768;&#26126;&#20026; noexcept</td>
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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2942">LWG 2942</a></td>
<td>C++11</td>
<td><code>weak_ptr::owner_before</code> &#22312; LWG 2873 &#30340;&#35299;&#20915;&#26041;&#26696;&#20013;&#32570;&#23569; noexcept</td>
<td>&#20196;&#20043;&#20026; noexcept</td>
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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-memory-owner_less.html"><span class="t-lines"><span>owner_less</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>&#25552;&#20379;&#22522;&#20110;&#25152;&#26377;&#32773;&#30340;&#65292;&#20849;&#20139;&#25351;&#38024;&#21644;&#24369;&#25351;&#38024;&#30340;&#28151;&#21512;&#31867;&#22411;&#30340;&#25490;&#24207;<br />
<span class="t-mark">(&#31867;&#27169;&#26495;)</span></td>
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