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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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<title>std::ranges::remove, std::ranges::remove_if</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_algorithm_ranges_remove 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::</span>remove, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>remove_if</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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<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></div>
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<td></td>
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<td></td>
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<div>调用签名</div>
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<td></td>
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<tr class="t-dcl t-since-cxx20">
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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">permutable</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, <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 /></span>
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<p>requires std<span class="sy4">::</span><span class="me2">indirect_binary_predicate</span><span class="sy1"><</span><br />
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ranges<span class="sy4">::</span><span class="me2">equal_to</span>, std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span><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 /></p>
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remove<span class="br0">(</span> I first, S last, <span class="kw4">const</span> T<span class="sy3">&</span> value, 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> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span> <span class="sy1">></span><br /></span>
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<p>requires std<span class="sy4">::</span><span class="me2">permutable</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="sy3">&&</span><br />
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std<span class="sy4">::</span><span class="me2">indirect_binary_predicate</span><span class="sy1"><</span><br />
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ranges<span class="sy4">::</span><span class="me2">equal_to</span>, std<span class="sy4">::</span><span class="me2">projected</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>, Proj<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span><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 /></p>
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remove<span class="br0">(</span> R<span class="sy3">&&</span> r, <span class="kw4">const</span> T<span class="sy3">&</span> value, 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 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">permutable</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> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">>></span> Pred <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 /></p>
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remove_if<span class="br0">(</span> I first, S last, Pred pred, 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>(3)</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> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</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>, Proj<span class="sy1">>></span> Pred <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">permutable</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><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 /></p>
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remove_if<span class="br0">(</span> R<span class="sy3">&&</span> r, Pred pred, 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>(4)</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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<p>从范围 <code>[first, last)</code> 移除所有满足特定判别标准的元素，并返回子范围 <code>[ret, last)</code> ，其中 <code>ret</code> 是范围新末尾的尾后迭代器。</p>
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<div class="t-li1"><span class="t-li">1)</span> 移除所有等于 <code>value</code> 的元素，用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><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>i<span class="br0">)</span> <span class="sy1">==</span> value</span></span> 比较。</div>
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<div class="t-li1"><span class="t-li">3)</span> 移除所有使得 <span class="t-c"><span class="mw-geshi cpp source-cpp"><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>i<span class="br0">)</span><span class="br0">)</span></span></span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 的元素。</div>
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<div class="t-li1"><span class="t-li">2,4)</span> 同 <span class="t-v">(1,3)</span> ，但以 <code>r</code> 为范围，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>通过使未被移除的元素出现在范围起始这种方式，迁移（方式为移动赋值）范围中元素，来进行移除。保持剩余元素的相对顺序而容器的<i>物理</i>大小保持不变。指向新的<i>逻辑</i>结尾与<i>物理</i>结尾之间的迭代器仍然可解引用，但元素自身拥有未指定的值（经由<a href="cpp-named_req-MoveAssignable.html"><span style="font-style:italic">可移动赋值</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(MoveAssignable)</span></a> 的后条件）。</p>
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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>要处理的元素范围</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>要处理的元素范围</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>要移除的元素的值</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>应用到投影后元素的谓词</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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<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">{</span>ret, last<span class="br0">}</span></span></span> ，其中 <code>[first, ret)</code> 是移除后作为结果的子范围，而子范围 <code>[ret, last)</code> 中的元素在合法但未指定的状态。</p>
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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>准确应用 <code>N</code> 次对应谓词和任何投影，其中 <span class="t-c"><span class="mw-geshi cpp source-cpp">N <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first, last<span class="br0">)</span></span></span> ，及最坏情况下 <span class="t-c"><span class="mw-geshi cpp source-cpp">N<span class="sy2">-</span><span class="nu0">1</span></span></span> 次移动操作。</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>调用 <code>ranges::remove</code> 常后随容器的 <code>erase</code> 成员函数，它擦除未指定值并减小容器的<i>物理</i>大小以匹配其新的<i>逻辑</i>大小。这两个调用一并被称为<a href="https://en.wikipedia.org/wiki/Erase-remove_idiom" class="extiw" title="enwiki:Erase-remove idiom"><i>擦除-移除</i>手法</a>，它可通过对所有标准<i>序列</i>容器重载的 <span class="t-lc">std::erase</span> 自由函数，或对<i>所有</i>标准容器重载的 <span class="t-lc">std::erase_if</span> 自由函数达成。</p>
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<p>名称类似的容器成员函数 <a href="cpp-container-list-remove.html"><tt>list::remove</tt></a>、 <a href="cpp-container-list-remove.html"><tt>list::remove_if</tt></a>、 <a href="cpp-container-forward_list-remove.html"><tt>forward_list::remove</tt></a> 及 <a href="cpp-container-forward_list-remove.html"><tt>forward_list::remove_if</tt></a> 擦除被移除的元素。</p>
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<p>这些算法通常不能用于如 <span class="t-lc"><a href="cpp-container-set.html">std::set</a></span> 与 <span class="t-lc"><a href="cpp-container-map.html">std::map</a></span> 的关联容器，因为其迭代器类型不解引用为<a href="cpp-named_req-MoveAssignable.html"><span style="font-style:italic">可移动赋值</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(MoveAssignable)</span></a> 类型（这些容器中的键不可修改）。</p>
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<p>因为 <code>ranges::remove</code> 按引用接收 <code>value</code> ，若它是到范围 <code>[first, last)</code> 中元素的引用则函数可能有非期待的行为。</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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<th>版本一</th>
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</tr>
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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> remove_fn <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">permutable</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, <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">indirect_binary_predicate</span><span class="sy1"><</span>
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ranges<span class="sy4">::</span><span class="me2">equal_to</span>, std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span><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, <span class="kw4">const</span> T<span class="sy3">&</span> value, 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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first <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">find</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first<span class="br0">)</span>, last, value, proj<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span>first <span class="sy3">!</span><span class="sy1">=</span> last<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span>I i <span class="br0">{</span> <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> i <span class="sy3">!</span><span class="sy1">=</span> last<span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span>value <span class="sy3">!</span><span class="sy1">=</span> <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>i<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="sy2">*</span>first <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">iter_move</span><span class="br0">(</span>i<span class="br0">)</span><span class="sy4">;</span>
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<span class="sy2">++</span>first<span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span>
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<span class="br0">}</span>
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||||
<span class="kw1">return</span> <span class="br0">{</span>first, last<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> 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">permutable</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="sy3">&&</span>
|
||||
std<span class="sy4">::</span><span class="me2">indirect_binary_predicate</span><span class="sy1"><</span>
|
||||
ranges<span class="sy4">::</span><span class="me2">equal_to</span>, std<span class="sy4">::</span><span class="me2">projected</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>, Proj<span class="sy1">></span>, <span class="kw4">const</span> T<span class="sy2">*</span><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, <span class="kw4">const</span> T<span class="sy3">&</span> value, 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>, value, 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> remove_fn remove<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
|
||||
</div>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<th>版本二</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>
|
||||
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
||||
<div class="cpp source-cpp">
|
||||
<pre class="de1"><span class="kw1">struct</span> remove_if_fn <span class="br0">{</span>
|
||||
<span class="kw1">template</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">permutable</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> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
|
||||
std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">>></span> Pred<span class="sy1">></span>
|
||||
<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">subrange</span><span class="sy1"><</span>I<span class="sy1">></span>
|
||||
operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> I first, S last, Pred pred, 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>
|
||||
first <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">find_if</span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first<span class="br0">)</span>, last, pred, proj<span class="br0">)</span><span class="sy4">;</span>
|
||||
<span class="kw1">if</span> <span class="br0">(</span>first <span class="sy3">!</span><span class="sy1">=</span> last<span class="br0">)</span> <span class="br0">{</span>
|
||||
<span class="kw1">for</span> <span class="br0">(</span>I i <span class="br0">{</span> <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> i <span class="sy3">!</span><span class="sy1">=</span> last<span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
|
||||
<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>i<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
|
||||
<span class="sy2">*</span>first <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">iter_move</span><span class="br0">(</span>i<span class="br0">)</span><span class="sy4">;</span>
|
||||
<span class="sy2">++</span>first<span class="sy4">;</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="br0">}</span>
|
||||
<span class="kw1">return</span> <span class="br0">{</span>first, last<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> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
|
||||
std<span class="sy4">::</span><span class="me2">indirect_unary_predicate</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</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>, Proj<span class="sy1">>></span> Pred<span class="sy1">></span>
|
||||
requires std<span class="sy4">::</span><span class="me2">permutable</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">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, Pred pred, 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>, pred, 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> remove_if_fn remove_if<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
|
||||
</div>
|
||||
</td>
|
||||
</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 <cctype></span>
|
||||
<span class="co2">#include <iomanip></span>
|
||||
<span class="co2">#include <iostream></span>
|
||||
|
||||
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
||||
<span class="br0">{</span>
|
||||
<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> ndr<span class="br0">{</span><span class="st0">"N o _ D i a g n o s t i c _ R e q u i r e d"</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-quoted.html"><span class="kw1802">std::<span class="me2">quoted</span></span></a><span class="br0">(</span>ndr<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" -> "</span><span class="sy4">;</span>
|
||||
<span class="kw4">const</span> <span class="kw4">auto</span> ret1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">remove</span><span class="br0">(</span>ndr, <span class="st0">' '</span><span class="br0">)</span><span class="sy4">;</span>
|
||||
ndr.<span class="me1">erase</span><span class="br0">(</span>ret1.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, ret1.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</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-quoted.html"><span class="kw1802">std::<span class="me2">quoted</span></span></a><span class="br0">(</span>ndr<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\n</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">auto</span> rm <span class="sy1">=</span> <span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">char</span> c<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> std<span class="sy4">::</span><span class="me2">islower</span><span class="br0">(</span>c<span class="br0">)</span> or std<span class="sy4">::</span><span class="me2">isspace</span><span class="br0">(</span>c<span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span>
|
||||
<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> sfinae<span class="br0">{</span><span class="st0">"Substitution Failure Is Not An Error"</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-quoted.html"><span class="kw1802">std::<span class="me2">quoted</span></span></a><span class="br0">(</span>sfinae<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" -> "</span><span class="sy4">;</span>
|
||||
<span class="kw4">const</span> <span class="kw4">auto</span> ret2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">remove_if</span><span class="br0">(</span>sfinae, rm<span class="br0">)</span><span class="sy4">;</span>
|
||||
sfinae.<span class="me1">erase</span><span class="br0">(</span>ret2.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, ret2.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</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-quoted.html"><span class="kw1802">std::<span class="me2">quoted</span></span></a><span class="br0">(</span>sfinae<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">"N o _ D i a g n o s t i c _ R e q u i r e d" -> "No_Diagnostic_Required"
|
||||
|
||||
"Substitution Failure Is Not An Error" -> "SFINAE"</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-remove_copy.html"><span class="t-lines"><span>ranges::remove_copy</span><span>ranges::remove_copy_if</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></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>复制一个范围的元素，忽略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-unique.html"><span class="t-lines"><span>ranges::unique</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>移除范围中的连续重复元素<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-remove.html"><span class="t-lines"><span>remove</span><span>remove_if</span></span></a></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>移除满足特定判别标准的元素<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