224 lines
19 KiB
HTML
224 lines
19 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_token_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_token_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_token_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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<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_token_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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<p><code>std::regex_token_iterator</code> 是访问底层字符序列内每个正则表达式匹配的单独子匹配的只读<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> 。它亦可用于访问不为给定的正则表达式所匹配的序列部分（例如作为记号化器）。</p>
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<p>构造时，它构造一个 <span class="t-lc"><a href="cpp-regex-regex_iterator.html">std::regex_iterator</a></span> ，而在每次自增时，它走过请求的来自当前 match_results 的子匹配，并在自增离开上个子匹配时自增底层的 <code>regex_iterator</code> 。</p>
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<p>默认构造的 <code>std::regex_token_iterator</code> 是序列尾迭代器。在抵达最后匹配的最后子匹配自增合法的 <code>std::regex_token_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>在恰好变为序列尾迭代器前，若请求的子匹配下标列表中出现 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">-</span><span class="nu0">1</span></span></span> （非匹配碎片），则 <code>std::regex_token_iterator</code> 可成为<i>后缀迭代器</i>。若解引用这种迭代器，则返回对应最后匹配和序列结尾之间的字符序列的 match_results 。</p>
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<p><code>std::regex_token_iterator</code> 的典型实现保有底层的 <span class="t-lc"><a href="cpp-regex-regex_iterator.html">std::regex_iterator</a></span> 、请求的子匹配下标的容器（例如 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span></span></span> ）、等于子匹配下标的内部计数器、指向当前匹配的当前子匹配的指向 <span class="t-lc"><a href="cpp-regex-sub_match.html">std::sub_match</a></span> 指针和含有最近非匹配字符序列的 <span class="t-lc"><a href="cpp-regex-match_results.html">std::match_results</a></span> 对象（用于记号化器模式）。</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>定义对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 class="t-dsc">
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<td><code>cregex_token_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_token_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_token_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_token_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_token_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_token_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 class="t-dsc">
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<td><code>wsregex_token_iterator</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">regex_token_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>
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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-sub_match.html"><span class="kw2002">std::<span class="me2">sub_match</span></span></a><span class="sy1"><</span>BidirIt<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>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>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 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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</tr>
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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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<td>
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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_token_iterator-regex_token_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_token_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_token_iterator</code> ，包含缓存值<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_token_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_token_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_token_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_token_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>访问当前子匹配<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_token_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子匹配<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.E6.84.8F">注意</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> 对象活得久于迭代器。因为迭代器存储 <span class="t-lc"><a href="cpp-regex-regex_iterator.html">std::regex_iterator</a></span> ，它存储指向 regex 的指针，故在销毁 regex 后自增迭代器导致未定义行为。</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 <fstream></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <algorithm></span>
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<span class="co2">#include <iterator></span>
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<span class="co2">#include <regex></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-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> text <span class="sy1">=</span> <span class="st0">"Quick brown fox."</span><span class="sy4">;</span>
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<span class="co1">// 记号化（非匹配碎片）</span>
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<span class="co1">// 注意仅匹配二次 regex ：在获得第三值时迭代器为后缀迭代器。</span>
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<a href="cpp-regex-basic_regex.html"><span class="kw2000">std::<span class="me2">regex</span></span></a> ws_re<span class="br0">(</span><span class="st0">"<span class="es1">\\</span>s+"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 空白符</span>
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<a href="cpp-algorithm-copy.html"><span class="kw1582">std::<span class="me2">copy</span></span></a><span class="br0">(</span> std<span class="sy4">::</span><span class="me2">sregex_token_iterator</span><span class="br0">(</span>text.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, text.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, ws_re, <span class="sy2">-</span><span class="nu0">1</span><span class="br0">)</span>,
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std<span class="sy4">::</span><span class="me2">sregex_token_iterator</span><span class="br0">(</span><span class="br0">)</span>,
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<a href="cpp-iterator-ostream_iterator.html"><span class="kw670">std::<span class="me2">ostream_iterator</span></span></a><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy1">></span><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>, <span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 迭代首个子匹配</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> html <span class="sy1">=</span> <span class="st0">"<p><a href=<span class="es1">\"</span>http://google.com<span class="es1">\"</span>>google</a> "</span>
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<span class="st0">"< a HREF =<span class="es1">\"</span>http://cppreference.com<span class="es1">\"</span>>cppreference</a><span class="es1">\n</span></p>"</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> url_re<span class="br0">(</span><span class="st0">"<<span class="es1">\\</span>s*A<span class="es1">\\</span>s+[^>]*href<span class="es1">\\</span>s*=<span class="es1">\\</span>s*<span class="es1">\"</span>([^<span class="es1">\"</span>]*)<span class="es1">\"</span>"</span>, std<span class="sy4">::</span><span class="me2">regex</span><span class="sy4">::</span><span class="me2">icase</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-algorithm-copy.html"><span class="kw1582">std::<span class="me2">copy</span></span></a><span class="br0">(</span> std<span class="sy4">::</span><span class="me2">sregex_token_iterator</span><span class="br0">(</span>html.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, html.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, url_re, <span class="nu0">1</span><span class="br0">)</span>,
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std<span class="sy4">::</span><span class="me2">sregex_token_iterator</span><span class="br0">(</span><span class="br0">)</span>,
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<a href="cpp-iterator-ostream_iterator.html"><span class="kw670">std::<span class="me2">ostream_iterator</span></span></a><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy1">></span><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>, <span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Quick
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brown
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fox.
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http://google.com
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http://cppreference.com</pre></div>
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</div>
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</div>
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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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