251 lines
18 KiB
HTML
251 lines
18 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::regex_iterator</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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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_regex_regex_iterator 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>regex_iterator</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-regex.html">regex</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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<td>
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<div>定义于头文件 <code><a href="cpp-header-regex.html"><regex></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 class="t-dcl t-since-cxx11">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><br /></span>
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<p> <span class="kw1">class</span> BidirIt,<br />
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<span class="kw1">class</span> CharT <span class="sy1">=</span> <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1"><</span>BidirIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span>,<br />
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<span class="kw1">class</span> Traits <span class="sy1">=</span> <a href="cpp-regex-regex_traits.html"><span class="kw2021">std::<span class="me2">regex_traits</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span><br /></p>
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<span class="sy1">></span> <span class="kw1">class</span> regex_iterator</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-since-cxx11">(C++11 起)</span></td>
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<td></td>
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<td></td>
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<p><code>std::regex_iterator</code> 是访问底层字符序列中正则表达式的单独匹配的只读<a href="cpp-named_req-ForwardIterator.html"><span style="font-style:italic">老式向前迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyForwardIterator)</span></a> 。</p>
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<p>在构造和每次自增时，它调用 <span class="t-lc"><a href="cpp-regex-regex_search.html">std::regex_search</a></span> 并记忆结果（即保存值 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-regex-match_results.html"><span class="kw2007">std::<span class="me2">match_results</span></span></a><span class="sy1"><</span>BidirIt<span class="sy1">></span></span></span> 的副本）。第一个对象可能在构造迭代器或进行首次解引用时读取。其他情况下，解引用只返回最近获得的正则表达式匹配副本。</p>
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<p>默认构造的 <code>std::regex_iterator</code> 是序列尾迭代器。在抵达最后匹配（<span class="t-lc"><a href="cpp-regex-regex_search.html">std::regex_search</a></span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> ）后自增合法的 <code>std::regex_iterator</code> 时，它变得等于序列尾迭代器。进一步解引用或自增它引发未定义行为。</p>
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<p>典型的 <code>std::regex_iterator</code> 实现保有底层序列的开始和结束迭代器（二个 BidirIt 实例）、指向正则表达式的指针（ <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> regex_type<span class="sy2">*</span></span></span> ）、匹配标志（ <span class="t-lc"><a href="cpp-regex-match_flag_type.html">std::regex_constants::match_flag_type</a></span> ）和当前匹配（ <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-regex-match_results.html"><span class="kw2007">std::<span class="me2">match_results</span></span></a><span class="sy1"><</span>BidirIt<span class="sy1">></span></span></span> ）。</p>
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<h3><span class="mw-headline" id=".E7.B1.BB.E5.9E.8B.E8.A6.81.E6.B1.82">类型要求</span></h3>
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<table class="t-par-begin">
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>BidirIt</code> 必须满足<a href="cpp-named_req-BidirectionalIterator.html"><span style="font-style:italic">老式双向迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyBidirectionalIterator)</span></a> 的要求。</td>
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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>提供对于常用字符序列类型的数个特化：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-header">
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<td colspan="2">
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<div>定义于头文件 <code><a href="cpp-header-regex.html"><regex></a></code></div>
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</td>
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</tr>
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<tr class="t-dsc-hitem">
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<td>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>cregex_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_iterator<span class="sy1"><</span><span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span><span class="sy1">></span></span></span></td>
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<tr class="t-dsc">
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<td><code>wcregex_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_iterator<span class="sy1"><</span><span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span><span class="sy1">></span></span></span></td>
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<tr class="t-dsc">
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<td><code>sregex_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_iterator<span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">string</span><span class="sy4">::</span><span class="me2">const_iterator</span><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>wsregex_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_iterator<span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">wstring</span><span class="sy4">::</span><span class="me2">const_iterator</span><span class="sy1">></span></span></span></td>
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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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<td>成员类型</td>
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<td>定义</td>
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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"><a href="cpp-regex-match_results.html"><span class="kw2007">std::<span class="me2">match_results</span></span></a><span class="sy1"><</span>BidirIt<span class="sy1">></span></span></span></td>
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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 class="t-dsc">
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<td><code>pointer</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> value_type<span class="sy2">*</span></span></span></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><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> value_type<span class="sy3">&</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><span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::forward_iterator_tag</a></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>regex_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">basic_regex<span class="sy1"><</span>CharT, Traits<span class="sy1">></span></span></span></td>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<table class="t-dsc-begin">
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-regex-regex_iterator-regex_iterator.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造新的 <code>regex_iterator</code><br />
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<span class="t-mark">(公开成员函数)</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 t-dsc-member-nobold-div">
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<div><span class="t-lines"><span>(析构函数)</span></span></div>
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<div><span class="t-lines"><span><span class="t-mark">(隐式声明)</span></span></span></div>
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</div>
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</td>
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<td>析构 <code>regex_iterator</code> ，包含缓存的值<br />
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<span class="t-mark">(公开成员函数)</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-regex-regex_iterator-operator=.html"><span class="t-lines"><span>operator=</span></span></a></div>
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</div>
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</td>
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<td>赋值内容<br />
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<span class="t-mark">(公开成员函数)</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-regex-regex_iterator-operator_cmp.html"><span class="t-lines"><span>operator==</span><span>operator!=</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span></span></div>
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</div>
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</td>
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<td>比较两个 <code>regex_iterator</code><br />
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<span class="t-mark">(公开成员函数)</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-regex-regex_iterator-operator*.html"><span class="t-lines"><span>operator*</span><span>operator-></span></span></a></div>
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</div>
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</td>
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<td>访问当前匹配<br />
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<span class="t-mark">(公开成员函数)</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-regex-regex_iterator-operator_arith.html"><span class="t-lines"><span>operator++</span><span>operator++<span class="t-dsc-small">(int)</span></span></span></a></div>
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</div>
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</td>
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<td>推进迭代器到下一个匹配<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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</table>
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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>程序员负责确保传递给迭代器构造函数的 <span class="t-lc"><a href="cpp-regex-basic_regex.html">std::basic_regex</a></span> 对象活得长于迭代器。因为迭代器存储指向 regex 的指针，故在销毁 regex 后自增迭代器会访问悬垂指针。</p>
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<p>若匹配的正则表达式部分仅是<a href="cpp-regex-ecmascript.html#.E6.96.AD.E8.A8.80">断言</a>（ <code>^</code> 、 <code>$</code> 、 <code>\b</code> 、 <code>\B</code> ），则存储于迭代器的匹配是零长度匹配，即 <span class="t-c"><span class="mw-geshi cpp source-cpp">match<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span>.<span class="me1">first</span> <span class="sy1">==</span> match<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span>.<span class="me1">second</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <regex></span>
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<span class="co2">#include <iterator></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <string></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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<span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> s <span class="sy1">=</span> <span class="st0">"Quick brown fox."</span><span class="sy4">;</span>
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<a href="cpp-regex-basic_regex.html"><span class="kw2000">std::<span class="me2">regex</span></span></a> words_regex<span class="br0">(</span><span class="st0">"[^<span class="es1">\\</span>s]+"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> words_begin <span class="sy1">=</span>
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std<span class="sy4">::</span><span class="me2">sregex_iterator</span><span class="br0">(</span>s.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, s.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, words_regex<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span> words_end <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">sregex_iterator</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Found "</span>
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<span class="sy1"><<</span> <a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>words_begin, words_end<span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">" words:<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span>std<span class="sy4">::</span><span class="me2">sregex_iterator</span> i <span class="sy1">=</span> words_begin<span class="sy4">;</span> i <span class="sy3">!</span><span class="sy1">=</span> words_end<span class="sy4">;</span> <span class="sy2">++</span>i<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-regex-match_results.html"><span class="kw2010">std::<span class="me2">smatch</span></span></a> match <span class="sy1">=</span> <span class="sy2">*</span>i<span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> match_str <span class="sy1">=</span> match.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> match_str <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="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">Found 3 words:
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Quick
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brown
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fox.</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-regex-match_results.html"><span class="t-lines"><span>match_results</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>标识一个正则表达式匹配，包含所有子表达式匹配<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-regex-regex_search.html"><span class="t-lines"><span>regex_search</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>尝试匹配一个正则表达式到字符序列的任何部分<br />
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<span class="t-mark">(函数模板)</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>
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<td></td>
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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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