64 lines
5.2 KiB
HTML
64 lines
5.2 KiB
HTML
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<title>std::ranges::elements_view<V,N>::iterator<Const>::operator[]</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_ranges_elements_view_iterator_operator_at 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::ranges::elements_view<V,N>::<i>iterator</i><Const>::</span>operator[]</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-ranges.html">ranges</a>‎ | <a href="cpp-ranges-elements_view.html">elements view</a>‎ | <a href="cpp-ranges-elements_view-iterator.html">iterator</a></span></div>
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<table class="t-dcl-begin">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> decltype<span class="br0">(</span><span class="kw4">auto</span><span class="br0">)</span> operator<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span> difference_type n <span class="br0">)</span> <span class="kw4">const</span><br />
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requires ranges<span class="sy4">::</span><span class="me2">random_access_range</span><span class="sy1"><</span>Base<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<td></td>
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<td></td>
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<td></td>
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<p>返回位于指定位置的元素。</p>
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<p>等效于返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*get-element*/</span><span class="br0">(</span>this<span class="sy2">-</span><span class="sy1">></span>base<span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> n<span class="br0">)</span></span></span> ，其中对于表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">e</span></span> ， <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*get-element*/</span><span class="br0">(</span>e<span class="br0">)</span></span></span> 为</p>
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">get</span><span class="sy1"><</span>N<span class="sy1">></span><span class="br0">(</span><span class="sy2">*</span>e<span class="br0">)</span></span></span> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">range_reference_t</span><span class="sy1"><</span>Base<span class="sy1">></span></span></span> 为引用类型，</li>
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<li>否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">static_cast</span><span class="sy1"><</span>E<span class="sy1">></span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">get</span><span class="sy1"><</span>N<span class="sy1">></span><span class="br0">(</span><span class="sy2">*</span>e<span class="br0">)</span><span class="br0">)</span></span></span> ，其中 <code>E</code> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-remove_cv.html"><span class="kw597">std::<span class="me2">remove_cv_t</span></span></a><span class="sy1"><</span><a href="cpp-utility-tuple-tuple_element.html"><span class="kw1100">std::<span class="me2">tuple_element_t</span></span></a><span class="sy1"><</span>N, ranges<span class="sy4">::</span><span class="me2">range_reference_t</span><span class="sy1"><</span>Base<span class="sy1">>>></span></span></span> 。</li>
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</ul>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>n</td>
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<td>-</td>
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<td>相对当前位置的位置</td>
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</tr>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>位于相对于当前位置位移为 <code>n</code> 的元素。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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