89 lines
6.0 KiB
HTML
89 lines
6.0 KiB
HTML
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::ranges::drop_while_view<V,Pred>::base</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_ranges_drop_while_view_base 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::drop_while_view<V,Pred>::</span>base</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-ranges.html">ranges</a>‎ | <a href="cpp-ranges-drop_while_view.html">drop while view</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> V base<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy3">&</span> requires std<span class="sy4">::</span><span class="me2">copy_constructible</span><span class="sy1"><</span>V<span class="sy1">></span><span class="sy4">;</span></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-cxx20">(C++20 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> V base<span class="br0">(</span><span class="br0">)</span> <span class="sy3">&&</span><span class="sy4">;</span></span></div>
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<td>(2)</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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<p>返回底层视图的副本。</p>
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<div class="t-li1"><span class="t-li">1)</span> 从底层视图复制构造结果。</div>
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<div class="t-li1"><span class="t-li">2)</span> 从底层视图移动构造结果。</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<p>（无）</p>
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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>底层视图的副本。</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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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <array></span>
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<span class="co2">#include <ranges></span>
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<span class="co2">#include <iostream></span>
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<span class="kw4">void</span> print<span class="br0">(</span><span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&</span> container<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> elem <span class="sy4">:</span> container<span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> elem <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-container-array.html"><span class="kw1268">std::<span class="me2">array</span></span></a> data<span class="br0">{</span> <span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span> <span class="br0">}</span><span class="sy4">;</span>
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print<span class="br0">(</span>data<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> stub <span class="sy1">=</span> <span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> x <span class="sy1"><</span> <span class="nu0">2</span><span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span>
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<span class="kw4">auto</span> view <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">drop_while_view</span><span class="br0">{</span> data, stub <span class="br0">}</span><span class="sy4">;</span>
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<span class="kw4">auto</span> base <span class="sy1">=</span> view.<span class="me1">base</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// `base` 指代 `data`</span>
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std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">reverse</span><span class="br0">(</span>base<span class="br0">)</span><span class="sy4">;</span> <span class="co1">//< 直接更改 `data`</span>
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print<span class="br0">(</span>data<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">1 2 3 4
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4 3 2 1</pre></div>
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