399 lines
26 KiB
HTML
399 lines
26 KiB
HTML
<!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::iterator_traits</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_iterator_iterator_traits 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::</span>iterator_traits</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-iterator.html">iterator</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-iterator.html"><iterator></a></code></div>
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<td></td>
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<td></td>
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<tr class="t-dcl">
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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> Iter <span class="sy1">></span><br />
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<span class="kw1">struct</span> iterator_traits<span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td class="t-dcl-nopad">
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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> T <span class="sy1">></span><br />
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<span class="kw1">struct</span> iterator_traits<span class="sy1"><</span>T<span class="sy2">*</span><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 class="t-dcl-nopad"></td>
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<tr class="t-dcl t-until-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> <span class="kw1">class</span> T <span class="sy1">></span><br />
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<span class="kw1">struct</span> iterator_traits<span class="sy1"><</span><span class="kw4">const</span> T<span class="sy2">*</span><span class="sy1">></span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</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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<p><code>std::iterator_traits</code> 是类型特征类，提供面对<a href="cpp-named_req-Iterator.html"><span style="font-style:italic">老式迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyIterator)</span></a> 类型的统一接口。这使得可以仅通过迭代器实现算法。</p>
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<p>能对用户定义的迭代器特化模板，使得即使不提供通常的 typedef 也能从迭代器取得信息。</p>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx20">
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<td>
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<p>用户定义特化可以定义成员类型 <code>iterator_concept</code> 为<a href="cpp-iterator-iterator_tags.html">迭代器类别标签</a>之一，以指示遵从该迭代器概念。</p>
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</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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</table>
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<h3><span class="mw-headline" id=".E6.A8.A1.E7.89.88.E5.BD.A2.E5.8F.82">模版形参</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>Iter</td>
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<td>-</td>
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<td>需要取得与之相关属性的迭代器类型</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td><code>Iter::difference_type</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><code>Iter::value_type</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td><code>Iter::pointer</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td><code>Iter::reference</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td><code>Iter::iterator_category</code></td>
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</tr>
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</table>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx17 t-until-cxx20">
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<td>
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<p>若 <code>Iter</code> 没有全部五个成员类型 <code>difference_type</code> 、 <code>value_type</code> 、 <code>pointer</code> 、 <code>reference</code> 及 <code>iterator_category</code> ，则此模板无任何有那些名称的成员（ <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">iterator_traits</span></span></span> 对 SFINAE 友好）</p>
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</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-rev t-since-cxx20">
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<td>
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<p>若 <code>Iter</code> 无 <code>pointer</code> ，但拥有全部其他四个成员类型，则按如下方式声明成员类型：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td><code>Iter::difference_type</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><code>Iter::value_type</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td><code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td><code>Iter::reference</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td><code>Iter::iterator_category</code></td>
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</tr>
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</table>
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<p>否则，若 <code>Iter</code> 满足仅为说明的概念 <a href="cpp-named_req-InputIterator.html#.E6.A6.82.E5.BF.B5"><tt>__LegacyInputIterator</tt></a> ，则按如下方式声明成员类型：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">incrementable_traits</span><span class="sy1"><</span>Iter<span class="sy1">></span><span class="sy4">::</span><span class="me2">difference_type</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">indirectly_readable_traits</span><span class="sy1"><</span>Iter<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td>若合法则为 <code>Iter::pointer</code> ，否则若合法则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">decltype<span class="br0">(</span>​<a href="cpp-utility-declval.html"><span class="kw1119">std::<span class="me2">declval</span></span></a><span class="sy1"><</span>Iter<span class="sy3">&</span><span class="sy1">></span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">operator</span><span class="sy2">-</span><span class="sy1">></span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> ，否则为 <code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td>若合法则为 <code>Iter::reference</code> ，否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">iter_reference_t</span><span class="sy1"><</span>Iter<span class="sy1">></span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td>若合法则为 <code>Iter::iterator_category</code> ，<br />
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否则若 <code>Iter</code> 满足 <a href="cpp-named_req-RandomAccessIterator.html#.E6.A6.82.E5.BF.B5"><tt>__LegacyRandomAccessIterator</tt></a>
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<p>则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::random_access_iterator_tag</a></span> ，<br />
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否则若 <code>Iter</code> 满足 <a href="cpp-named_req-BidirectionalIterator.html#.E6.A6.82.E5.BF.B5"><tt>__LegacyBidirectionalIterator</tt></a> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::bidirectional_iterator_tag</a></span> ，<br />
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否则若 <code>Iter</code> 满足 <a href="cpp-named_req-ForwardIterator.html#.E6.A6.82.E5.BF.B5"><tt>__LegacyForwardIterator</tt></a> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::forward_iterator_tag</a></span> ，<br />
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否则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::input_iterator_tag</a></span></p>
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</td>
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</tr>
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</table>
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<p>否则，若 <code>Iter</code> 满足仅为说明的概念 <a href="cpp-named_req-Iterator.html#.E6.A6.82.E5.BF.B5"><tt>__LegacyIterator</tt></a> ，则按如下方式声明成员类型：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td>若合法则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">incrementable_traits</span><span class="sy1"><</span>Iter<span class="sy1">></span><span class="sy4">::</span><span class="me2">difference_type</span></span></span> ，否则为 <code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td><code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td><code>void</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td><code>std::output_iterator_tag</code></td>
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</tr>
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</table>
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<p>否则，此模板无任何有这些名称的成员此模板无任何有那些名称的成员（ <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">iterator_traits</span></span></span> 对 SFINAE 友好）。</p>
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</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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</table>
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<h3><span class="mw-headline" id=".E7.89.B9.E5.8C.96">特化</span></h3>
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<p>如果要把用户提供的类型作为迭代器使用，该类型特征可以针对这一类型进行特化。标准库中提供了针对指针类型 <code>T *</code> 的两种偏特化，使得可以在任何需要迭代器的算法里使用裸指针。</p>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx20">
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<td>
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<p>标准库亦提供对一些标准迭代器适配器的特化。</p>
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</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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</table>
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<h4><span class="mw-headline" id="T_.2A_.E7.89.B9.E5.8C.96.E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B"><code>T *</code> 特化成员类型</span></h4>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx20">
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<td>
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<p>仅若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-is_object.html"><span class="kw487">std::<span class="me2">is_object_v</span></span></a><span class="sy1"><</span>T<span class="sy1">></span></span></span> 为 <code>true</code> 才特化。</p>
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</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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</table>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td><span class="t-lc"><a href="cpp-types-ptrdiff_t.html">std::ptrdiff_t</a></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><span class="t-rev-inl t-until-cxx20"><span><code>T</code></span> <span><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></span></span><span class="t-rev-inl t-since-cxx20"><span><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>T<span class="sy1">></span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td><code>T*</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td><code>T&</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td><span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::random_access_iterator_tag</a></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_concept</code><span class="t-mark-rev t-since-cxx20">(C++20)</span></td>
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<td><span class="t-lc">std::contiguous_iterator_tag</span></td>
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</tr>
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</table>
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<table class="t-rev-begin">
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<tr class="t-rev t-until-cxx20">
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<td>
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<h4><span class="mw-headline" id="const_T_.2A_.E7.89.B9.E5.8C.96.E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B"><code>const T *</code> 特化成员类型</span></h4>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>difference_type</code></td>
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<td><span class="t-lc"><a href="cpp-types-ptrdiff_t.html">std::ptrdiff_t</a></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>value_type</code></td>
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<td><code>T</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>pointer</code></td>
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<td><code>const T*</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>reference</code></td>
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<td><code>const T&</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>iterator_category</code></td>
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<td><span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::random_access_iterator_tag</a></span></td>
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</tr>
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</table>
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</td>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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</table>
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<h4><span class="mw-headline" id=".E5.AF.B9.E5.BA.93.E7.B1.BB.E5.9E.8B.E7.9A.84.E7.89.B9.E5.8C.96">对库类型的特化</span></h4>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-iterator-common_iterator-iterator_traits.html"><span class="t-lines"><span>std::iterator_traits<span class="t-dsc-small"><std::common_iterator></span></span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>对 <span class="t-lc">std::counted_iterator</span> 类型的属性提供均一的接口<br />
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<span class="t-mark">(类模板特化)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-iterator-counted_iterator-iterator_traits.html"><span class="t-lines"><span>std::iterator_traits<span class="t-dsc-small"><std::counted_iterator></span></span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>对 <span class="t-lc">std::counted_iterator</span> 类型的属性提供均一的接口<br />
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<span class="t-mark">(类模板特化)</span></td>
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</tr>
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</table>
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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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<p>下列使用展示对双向迭代器的通用 <code>reverse()</code> 实现</p>
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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 <iostream></span>
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<span class="co2">#include <iterator></span>
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<span class="co2">#include <vector></span>
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<span class="co2">#include <list></span>
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<span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> BidirIt<span class="sy1">></span>
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<span class="kw4">void</span> my_reverse<span class="br0">(</span>BidirIt first, BidirIt last<span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw1">typename</span> std<span class="sy4">::</span><span class="me2">iterator_traits</span><span class="sy1"><</span>BidirIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">difference_type</span> n <span class="sy1">=</span> <a href="cpp-iterator-distance.html"><span class="kw672">std::<span class="me2">distance</span></span></a><span class="br0">(</span>first, last<span class="br0">)</span><span class="sy4">;</span>
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<span class="sy2">--</span>n<span class="sy4">;</span>
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<span class="kw1">while</span><span class="br0">(</span>n <span class="sy1">></span> <span class="nu0">0</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">typename</span> std<span class="sy4">::</span><span class="me2">iterator_traits</span><span class="sy1"><</span>BidirIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span> tmp <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
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<span class="sy2">*</span>first<span class="sy2">++</span> <span class="sy1">=</span> <span class="sy2">*--</span>last<span class="sy4">;</span>
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<span class="sy2">*</span>last <span class="sy1">=</span> tmp<span class="sy4">;</span>
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n <span class="sy2">-</span><span class="sy1">=</span> <span class="nu0">2</span><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="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-vector.html"><span class="kw1268">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> v<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="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
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my_reverse<span class="br0">(</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> n <span class="sy4">:</span> v<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> n <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1757">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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<a href="cpp-container-list.html"><span class="kw1274">std::<span class="me2">list</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> l<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="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
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my_reverse<span class="br0">(</span>l.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, l.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">auto</span> n <span class="sy4">:</span> l<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> n <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1757">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="kw4">int</span> a<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <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="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
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my_reverse<span class="br0">(</span>a, a<span class="sy2">+</span><span class="nu0">5</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> i<span class="sy1">=</span><span class="nu0">0</span><span class="sy4">;</span> i<span class="sy1"><</span><span class="nu0">5</span><span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> a<span class="br0">[</span>i<span class="br0">]</span> <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="cpp-io-cout.html"><span class="kw1757">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="co1">// std::istreambuf_iterator<char> i1(std::cin), i2;</span>
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<span class="co1">// my_reverse(i1, i2); // 编译错误</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">5 4 3 2 1
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5 4 3 2 1
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5 4 3 2 1</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
|
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<td>
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<div class="t-dsc-member-div">
|
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<div><a href="cpp-iterator-iterator.html"><span class="t-lines"><span>iterator</span></span></a></div>
|
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<div><span class="t-lines"><span><span class="t-mark-rev t-deprecated-cxx17">(C++17 中弃用)</span></span></span></div>
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</div>
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</td>
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<td>用于简化简单的迭代器的必要类型定义的基类<br />
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<span class="t-mark">(类模板)</span></td>
|
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</tr>
|
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<tr class="t-dsc">
|
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-iterator-iterator_tags.html"><span class="t-lines"><span>input_iterator_tag</span><span>output_iterator_tag</span><span>forward_iterator_tag</span><span>bidirectional_iterator_tag</span><span>random_access_iterator_tag</span><span>contiguous_iterator_tag</span></span></a></div>
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<div><span class="t-lines"><span></span><span></span><span></span><span></span><span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>用于指示迭代器类别的空类类型<br />
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<span class="t-mark">(类)</span></td>
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</tr>
|
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</table>
|
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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