56 lines
3.8 KiB
HTML
56 lines
3.8 KiB
HTML
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<title>std::experimental::ranges::StrictWeakOrder</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_ranges_concepts_StrictWeakOrder skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::experimental::ranges::</span>StrictWeakOrder</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-experimental.html">experimental</a>‎ | <a href="cpp-experimental-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-experimental-ranges-concepts.html"><experimental/ranges/concepts></a></code></div>
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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> R, <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br />
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concept <span class="kw4">bool</span> StrictWeakOrder <span class="sy1">=</span> <a href="cpp-experimental-ranges-concepts-Relation.html"><span class="kw2559">ranges::<span class="me2">Relation</span></span></a><span class="sy1"><</span>R, T, U<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-ranges-ts t-mark-ts">(范围 TS)</span></td>
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<p>概念 <code>StrictWeakOrder<R, T, U></code> 指定 <a href="cpp-experimental-ranges-concepts-Relation.html"><code>Relation</code></a> <code>R</code> 蕴含其参数上的严格弱序。若满足下列条件则 <code>r</code> 是严格弱序</p>
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<li>非自反：对于所有 <code>x</code> ， <code>r(x, x)</code> 为 false ；</li>
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<li>传递：对于所有 <code>a</code> 、 <code>b</code> 和 <code>c</code> ，若 <code>r(a, b)</code> 和 <code>r(b, c)</code> 都为 true 则 <code>r(a, c)</code> 为 true ；</li>
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<li>令 <code>e(a, b)</code> 为 <code>!r(a, b) && !r(b, a)</code> ，则 <code>e</code> 是传递的： <code>e(a, b) && e(b, c)</code> 蕴含 <code>e(a, c)</code> 。</li>
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</ul>
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<p>在这些条件下，能证明 <code>e</code> 是等价关系，而 <code>r</code> 在 <code>e</code> 所确定的等价类上引入严格全序。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p><a href="cpp-experimental-ranges-concepts-Relation.html"><code>Relation</code></a> 与 <code>StrictWeakOrder</code> 间的区别是纯语义的。</p>
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