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<!DOCTYPE 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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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>std::ranges::search_n</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_algorithm_ranges_search_n skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>search_n</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-algorithm.html">algorithm</a>‎ | <a href="cpp-algorithm-ranges.html">ranges</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></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-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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<tr class="t-dcl-h">
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<td>
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<div>调用签名</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-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> std<span class="sy4">::</span><span class="me2">forward_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I<span class="sy1">></span> S, <span class="kw1">class</span> T,<br /></span>
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<p> <span class="kw1">class</span> Pred <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span>, <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">indirectly_comparable</span><span class="sy1"><</span>I, <span class="kw4">const</span> T<span class="sy2">*</span>, Pred, Proj<span class="sy1">></span><br />
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">subrange</span><span class="sy1"><</span>I<span class="sy1">></span><br />
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search_n<span class="br0">(</span> I first, S last, std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1"><</span>I<span class="sy1">></span> count,<br /></p>
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<span class="kw4">const</span> T<span class="sy3">&</span> value, Pred pred <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</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-cxx20">(C++20 起)</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> ranges<span class="sy4">::</span><span class="me2">forward_range</span> R, <span class="kw1">class</span> T, <span class="kw1">class</span> Pred <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span>,<br /></span>
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<p> <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">indirectly_comparable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span>, Pred, Proj<span class="sy1">></span><br />
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">borrowed_subrange_t</span><span class="sy1"><</span>R<span class="sy1">></span><br />
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search_n<span class="br0">(</span> R<span class="sy3">&&</span> r, ranges<span class="sy4">::</span><span class="me2">range_difference_t</span><span class="sy1"><</span>R<span class="sy1">></span> count,<br /></p>
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<span class="kw4">const</span> T<span class="sy3">&</span> value, Pred pred <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</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-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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<div class="t-li1"><span class="t-li">1)</span> 在范围 <code>[first, last)</code> 中搜索<i>首个</i> <code>count</code> 元素的序列,其投影后的值按照二元谓词 <code>pred</code> 等于给定的值 <code>value</code> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ,但以 <code>r</code> 为源范围,如同以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span></span></span> 为 <code>first</code> 并以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span></span></span> 为 <code>last</code> 。</div>
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<p>此页面上描述的仿函数实体是 <i>niebloid</i> ,即:</p>
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<ul>
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<li>调用它们中的任何一者时不可指定显式模板实参。</li>
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<li>它们无一对<a href="cpp-language-adl.html">实参依赖查找</a>可见。</li>
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<li>在<a href="cpp-language-unqualified_lookup.html">通常无限定查找</a>寻找函数调用运算符左侧的名称找到它们之一时,它禁止<a href="cpp-language-adl.html">实参依赖查找</a>。</li>
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||||
</ul>
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||||
<p>实际上,它们能以函数对象,或以某些特殊编译器扩展实现。</p>
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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>first, last</td>
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<td>-</td>
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<td>要检验的元素范围(又称<i>草堆</i>)</td>
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</tr>
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<tr class="t-par">
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<td>r</td>
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<td>-</td>
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<td>要检验的元素范围(又称<i>草堆</i>)</td>
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</tr>
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||||
<tr class="t-par">
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<td>count</td>
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<td>-</td>
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<td>要搜索的序列长度</td>
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</tr>
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<tr class="t-par">
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<td>value</td>
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<td>-</td>
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<td>要搜索的值(又称<i>针</i>)</td>
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</tr>
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<tr class="t-par">
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<td>pred</td>
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<td>-</td>
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<td>比较投影后元素与 <code>value</code> 的二元谓词</td>
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</tr>
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<tr class="t-par">
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<td>proj</td>
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<td>-</td>
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<td>应用到要检验的范围的元素的投影</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>
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<div class="t-li1"><span class="t-li">1)</span> 返回含有范围 <code>[first, last)</code> 中指代找到的序列的一对迭代器的 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">subrange</span></span></span> 。
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<p>若找不到这种序列,则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">subrange</span><span class="br0">{</span>last, last<span class="br0">}</span></span></span> 。</p>
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若 <span class="t-c"><span class="mw-geshi cpp source-cpp">count ≤ <span class="nu0">0</span></span></span> 则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">subrange</span><span class="br0">{</span>first, first<span class="br0">}</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ,但返回类型为 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">borrowed_subrange_t</span><span class="sy1"><</span>R<span class="sy1">></span></span></span> 。</div>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<p>线性:至多应用 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first, last<span class="br0">)</span></span></span> 次谓词与投影。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>若迭代器实现 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">random_access_iterator</span></span></span> 则实现可以提升<i>平均</i>搜索效率。</p>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
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<table class="eq-fun-cpp-table">
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<tr>
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<td>
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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="kw1">struct</span> search_n_fn
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<span class="br0">{</span>
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<span class="kw1">template</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">forward_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I<span class="sy1">></span> S, <span class="kw1">class</span> T,
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<span class="kw1">class</span> Pred <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span>, <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span><span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">indirectly_comparable</span><span class="sy1"><</span>I, <span class="kw4">const</span> T<span class="sy2">*</span>, Pred, Proj<span class="sy1">></span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">subrange</span><span class="sy1"><</span>I<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>I first, S last, std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1"><</span>I<span class="sy1">></span> count,
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<span class="kw4">const</span> T<span class="sy3">&</span> value, Pred pred <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span>count <span class="sy1"><=</span> <span class="nu0">0</span><span class="br0">)</span>
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<span class="kw1">return</span> <span class="br0">{</span>first, first<span class="br0">}</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;</span> first <span class="sy3">!</span><span class="sy1">=</span> last<span class="sy4">;</span> <span class="sy2">++</span>first<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>pred, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, <span class="sy2">*</span>first<span class="br0">)</span>, value<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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I start <span class="sy1">=</span> first<span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1"><</span>I<span class="sy1">></span> n<span class="br0">{</span><span class="nu0">1</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;;</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span>n<span class="sy2">++</span> <span class="sy1">==</span> count<span class="br0">)</span>
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<span class="kw1">return</span> <span class="br0">{</span>start, <a href="cpp-iterator-next.html"><span class="kw674">std::<span class="me2">next</span></span></a><span class="br0">(</span>first<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span> <span class="co1">// 找到</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="sy2">++</span>first <span class="sy1">==</span> last<span class="br0">)</span>
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<span class="kw1">return</span> <span class="br0">{</span>first, first<span class="br0">}</span><span class="sy4">;</span> <span class="co1">// 找不到</span>
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||||
<span class="kw1">if</span> <span class="br0">(</span><span class="sy3">!</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>pred, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, <span class="sy2">*</span>first<span class="br0">)</span>, value<span class="br0">)</span><span class="br0">)</span>
|
||||
<span class="kw1">break</span><span class="sy4">;</span> <span class="co1">// not equ to value</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="kw1">return</span> <span class="br0">{</span>first, first<span class="br0">}</span><span class="sy4">;</span>
|
||||
<span class="br0">}</span>
|
||||
|
||||
<span class="kw1">template</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">forward_range</span> R, <span class="kw1">class</span> T, <span class="kw1">class</span> Pred <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span>,
|
||||
<span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span><span class="sy1">></span>
|
||||
requires std<span class="sy4">::</span><span class="me2">indirectly_comparable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span>, Pred, Proj<span class="sy1">></span>
|
||||
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">borrowed_subrange_t</span><span class="sy1"><</span>R<span class="sy1">></span>
|
||||
operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span>R<span class="sy3">&&</span> r, ranges<span class="sy4">::</span><span class="me2">range_difference_t</span><span class="sy1"><</span>R<span class="sy1">></span> count,
|
||||
<span class="kw4">const</span> T<span class="sy3">&</span> value, Pred pred <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
|
||||
<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span>,
|
||||
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>count<span class="br0">)</span>, value,
|
||||
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>pred<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>proj<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="br0">}</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw1">inline</span> <span class="kw4">constexpr</span> search_n_fn search_n<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
|
||||
</div>
|
||||
</td>
|
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</tr>
|
||||
</table>
|
||||
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
||||
<div class="t-example">
|
||||
<div class="t-example-live-link"></div>
|
||||
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
||||
<div class="cpp source-cpp">
|
||||
<pre class="de1"><span class="co2">#include <algorithm></span>
|
||||
<span class="co2">#include <iomanip></span>
|
||||
<span class="co2">#include <iostream></span>
|
||||
<span class="co2">#include <string></span>
|
||||
|
||||
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
||||
<span class="br0">{</span>
|
||||
<span class="kw4">static</span> <span class="kw4">constexpr</span> <span class="kw4">auto</span> nums <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">2</span>, <span class="nu0">3</span>, <span class="nu0">4</span>, <span class="nu0">1</span>, <span class="nu0">2</span>, <span class="nu0">2</span>, <span class="nu0">2</span>, <span class="nu0">1</span><span class="br0">}</span><span class="sy4">;</span>
|
||||
<span class="kw4">constexpr</span> <span class="kw4">int</span> count<span class="br0">{</span> <span class="nu0">3</span> <span class="br0">}</span><span class="sy4">;</span>
|
||||
<span class="kw4">constexpr</span> <span class="kw4">int</span> value<span class="br0">{</span> <span class="nu0">2</span> <span class="br0">}</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">constexpr</span> <span class="kw4">auto</span> result1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">search_n</span><span class="br0">(</span>
|
||||
nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, nums.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, count, value
|
||||
<span class="br0">)</span><span class="sy4">;</span>
|
||||
static_assert<span class="br0">(</span> <span class="co1">// 找到</span>
|
||||
result1.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> count <span class="sy3">&&</span>
|
||||
<a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, result1.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">6</span> <span class="sy3">&&</span>
|
||||
<a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, result1.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">9</span>
|
||||
<span class="br0">)</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">constexpr</span> <span class="kw4">auto</span> result2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">search_n</span><span class="br0">(</span>nums, count, value<span class="br0">)</span><span class="sy4">;</span>
|
||||
static_assert<span class="br0">(</span> <span class="co1">// 找到</span>
|
||||
result2.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> count <span class="sy3">&&</span>
|
||||
<a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, result2.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">6</span> <span class="sy3">&&</span>
|
||||
<a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, result2.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">9</span>
|
||||
<span class="br0">)</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">constexpr</span> <span class="kw4">auto</span> result3 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">search_n</span><span class="br0">(</span>nums, count, <span class="coMULTI">/* value */</span> <span class="nu0">5</span><span class="br0">)</span><span class="sy4">;</span>
|
||||
static_assert<span class="br0">(</span> <span class="co1">// 找不到</span>
|
||||
result3.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">0</span> <span class="sy3">&&</span>
|
||||
result3.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> result3.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&&</span>
|
||||
result3.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> nums.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>
|
||||
<span class="br0">)</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">constexpr</span> <span class="kw4">auto</span> result4 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">search_n</span><span class="br0">(</span>nums, <span class="coMULTI">/* count */</span> <span class="nu0">0</span>, <span class="coMULTI">/* value */</span> <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
|
||||
static_assert<span class="br0">(</span> <span class="co1">// 找不到</span>
|
||||
result4.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="nu0">0</span> <span class="sy3">&&</span>
|
||||
result4.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> result4.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&&</span>
|
||||
result4.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> nums.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>
|
||||
<span class="br0">)</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">constexpr</span> <span class="kw4">char</span> symbol<span class="br0">{</span><span class="st0">'B'</span><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"><<</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1764">std::<span class="me2">boolalpha</span></span></a> <span class="sy1"><<</span> <span class="st0">"Find a sub-sequence: "</span>
|
||||
<span class="sy1"><<</span> <a href="cpp-io-manip-quoted.html"><span class="kw1802">std::<span class="me2">quoted</span></span></a><span class="br0">(</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="br0">(</span>count, symbol<span class="br0">)</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">auto</span> result5 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">search_n</span><span class="br0">(</span>nums, count, symbol,
|
||||
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">const</span> <span class="kw4">char</span> x, <span class="kw4">const</span> <span class="kw4">char</span> y<span class="br0">)</span> <span class="br0">{</span> <span class="co1">// 二元谓词</span>
|
||||
<span class="kw4">const</span> <span class="kw4">bool</span> o<span class="br0">{</span> x <span class="sy1">==</span> y <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"><<</span> <span class="st0">"bin_op("</span> <span class="sy1"><<</span> x <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> y <span class="sy1"><<</span> <span class="st0">") == "</span> <span class="sy1"><<</span> o <span class="sy1"><<</span> <span class="st0">"<span class="es1">\n</span>"</span><span class="sy4">;</span>
|
||||
<span class="kw1">return</span> o<span class="sy4">;</span>
|
||||
<span class="br0">}</span>,
|
||||
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">const</span> <span class="kw4">int</span> z<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> <span class="st0">'A'</span> <span class="sy2">+</span> z <span class="sy2">-</span> <span class="nu0">1</span><span class="sy4">;</span> <span class="br0">}</span> <span class="co1">// 投影数字 -> ASCII</span>
|
||||
<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"><<</span> <span class="st0">"Found: "</span> <span class="sy1"><<</span> <span class="sy3">!</span>result5.<span class="me1">empty</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
||||
<span class="br0">}</span></pre></div>
|
||||
</div>
|
||||
<p>输出:</p>
|
||||
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
||||
<div class="text source-text">
|
||||
<pre class="de1">Find a sub-sequence: "BBB"
|
||||
bin_op(A, B) == false
|
||||
bin_op(B, B) == true
|
||||
bin_op(B, B) == true
|
||||
bin_op(C, B) == false
|
||||
bin_op(D, B) == false
|
||||
bin_op(A, B) == false
|
||||
bin_op(B, B) == true
|
||||
bin_op(B, B) == true
|
||||
bin_op(B, B) == true
|
||||
Found: true</pre></div>
|
||||
</div>
|
||||
</div>
|
||||
<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-algorithm-ranges-adjacent_find.html"><span class="t-lines"><span>ranges::adjacent_find</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>查找首对相邻的相同(或满足给定谓词的)元素<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-find.html"><span class="t-lines"><span>ranges::find</span><span>ranges::find_if</span><span>ranges::find_if_not</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>寻找首个满足特定判别标准的元素<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-find_end.html"><span class="t-lines"><span>ranges::find_end</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>在特定范围中寻找最后出现的元素序列<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-find_first_of.html"><span class="t-lines"><span>ranges::find_first_of</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>搜索元素集合中的任一元素<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-includes.html"><span class="t-lines"><span>ranges::includes</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>若一个序列是另一个的子列则返回 <code>true</code><br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-mismatch.html"><span class="t-lines"><span>ranges::mismatch</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>寻找两个范围出现不同的首个位置<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-ranges-search.html"><span class="t-lines"><span>ranges::search</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>搜索一个元素范围<br />
|
||||
<span class="t-mark">(niebloid)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-algorithm-search_n.html"><span class="t-lines"><span>search_n</span></span></a></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>在范围中搜索一定量的某个元素的连续副本<br />
|
||||
<span class="t-mark">(函数模板)</span></td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
<div class="visualClear"></div>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user