267 lines
18 KiB
HTML
267 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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<title>std::istreambuf_iterator</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_iterator_istreambuf_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>istreambuf_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-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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<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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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> CharT, <span class="kw1">class</span> Traits <span class="sy1">=</span> <a href="cpp-string-char_traits.html"><span class="kw1266">std::<span class="me2">char_traits</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span> <span class="sy1">></span><br /></span>
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<p><span class="kw1">class</span> istreambuf_iterator <span class="sy4">:</span> <span class="kw1">public</span> <a href="cpp-iterator-iterator.html"><span class="kw657">std::<span class="me2">iterator</span></span></a><span class="sy1"><</span> <a href="cpp-iterator-iterator_tags.html"><span class="kw652">std::<span class="me2">input_iterator_tag</span></span></a>,<br />
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CharT,<br />
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<span class="kw1">typename</span> Traits<span class="sy4">::</span><span class="me2">off_type</span>,<br />
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<span class="coMULTI">/* unspecified, usually CharT* */</span>,<br /></p>
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CharT <span class="sy1">></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-cxx17">(C++17 前)</span></td>
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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> CharT, <span class="kw1">class</span> Traits <span class="sy1">=</span> <a href="cpp-string-char_traits.html"><span class="kw1266">std::<span class="me2">char_traits</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span> <span class="sy1">></span><br />
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<span class="kw1">class</span> istreambuf_iterator<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-since-cxx17">(C++17 起)</span></td>
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<p><code>std::istreambuf_iterator</code> 是单趟迭代器,从为之构造迭代器的 <span class="t-lc"><a href="cpp-io-basic_streambuf.html">std::basic_streambuf</a></span> 对象读取相继字符。</p>
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<p>默认构造的 <code>std::istreambuf_iterator</code> 迭代器被称为<i>流尾</i>迭代器。合法的 <code>std::istreambuf_iterator</code> 抵达底层流结尾时,它变得等于流尾迭代器。解引用或进一步自增它导致未定义行为。</p>
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<p><code>std::istreambuf_iterator</code> 拥有平凡复制构造函数、 constexpr 默认构造函数和平凡析构函数。</p>
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</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</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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<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>iterator_category</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-iterator-iterator_tags.html"><span class="kw652">std::<span class="me2">input_iterator_tag</span></span></a></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">CharT</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-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">off_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><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/* unspecified, usually CharT* */</span></span></span></td>
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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">CharT</span></span></td>
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<tr class="t-dsc">
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<td><code>char_type</code></td>
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<td><code>CharT</code></td>
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<tr class="t-dsc">
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<td><code>traits_type</code></td>
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<td><code>Traits</code></td>
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<tr class="t-dsc">
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<td><code>int_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">typename</span> traits<span class="sy4">::</span><span class="me2">int_type</span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>streambuf_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-io-basic_streambuf.html"><span class="kw1665">std::<span class="me2">basic_streambuf</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span></span></span></td>
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<td><code>istream_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-io-basic_istream.html"><span class="kw1712">std::<span class="me2">basic_istream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span></span></span></td>
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<tr class="t-dsc">
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<td><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/* proxy */</span></span></td>
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<td>实现定义的类类型。名称 <code><i>proxy</i></code> 仅为说明。<br />
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<code><i>proxy</i></code> 对象保有一个 <code>char_type</code> 字符和一个 <code>streambuf_type*</code> 指针。<br />
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以 <code>operator*</code> 解引用 <code><i>proxy</i></code> 对象得到存储的字符。</td>
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<td>
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<p>要求通过从 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-iterator-iterator.html"><span class="kw657">std::<span class="me2">iterator</span></span></a><span class="sy1"><</span><a href="cpp-iterator-iterator_tags.html"><span class="kw652">std::<span class="me2">input_iterator_tag</span></span></a>, CharT, Traits<span class="sy4">::</span><span class="me2">off_type</span>, <span class="coMULTI">/* unspecified, usually CharT* */</span>, CharT<span class="sy1">></span></span></span> 继承获得成员类型 <code>iterator_category</code>、 <code>value_type</code>、 <code>difference_type</code>、 <code>pointer</code> 及 <code>reference</code> 。</p>
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</td>
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<td><span class="t-mark-rev t-until-cxx17">(C++17 前)</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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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-iterator-istreambuf_iterator-istreambuf_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>istreambuf_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>istreambuf_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-iterator-istreambuf_iterator-operator*.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-since-cxx11">(C++11 起)</span><span class="t-mark-rev t-until-cxx17">(C++17 前)</span></span></span></div>
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</div>
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</td>
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<td>获得当前字符的副本<br />
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若 <code>CharT</code> 拥有成员,则访问当前字符的成员<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-iterator-istreambuf_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<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-iterator-istreambuf_iterator-equal.html"><span class="t-lines"><span>equal</span></span></a></div>
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</div>
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</td>
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<td>测试两个 <code>istreambuf_iterator</code> 是否均为流尾或均合法<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=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</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-istreambuf_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>istreambuf_iterator</code><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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<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 <string></span>
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<span class="co2">#include <sstream></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <iterator></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="co1">// 典型使用情况:以一对迭代器表示的输入流</span>
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<a href="cpp-io-basic_istringstream.html"><span class="kw1734">std::<span class="me2">istringstream</span></span></a> in<span class="br0">{</span><span class="st0">"Hello, world"</span><span class="br0">}</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">istreambuf_iterator</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span> it<span class="br0">{</span>in<span class="br0">}</span>, end<span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1229">std::<span class="me2">string</span></span></a> ss<span class="br0">{</span>it, end<span class="br0">}</span><span class="sy4">;</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">"ss has "</span> <span class="sy1"><<</span> ss.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" bytes; "</span>
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<span class="st0">"it holds <span class="es1">\"</span>"</span> <span class="sy1"><<</span> ss <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="co1">// 演示单趟本性</span>
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<a href="cpp-io-basic_istringstream.html"><span class="kw1734">std::<span class="me2">istringstream</span></span></a> s<span class="br0">{</span><span class="st0">"abc"</span><span class="br0">}</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">istreambuf_iterator</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span> i1<span class="br0">{</span>s<span class="br0">}</span>, i2<span class="br0">{</span>s<span class="br0">}</span><span class="sy4">;</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">"i1 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i1 <span class="sy1"><<</span> <span class="st0">"'<span class="es1">\n</span>"</span>
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<span class="st0">"i2 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i2 <span class="sy1"><<</span> <span class="st0">"'<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="sy2">++</span>i1<span class="sy4">;</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">"after incrementing i1, but not i2<span class="es1">\n</span>"</span>
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<span class="st0">"i1 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i1 <span class="sy1"><<</span> <span class="st0">"'<span class="es1">\n</span>"</span>
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<span class="st0">"i2 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i2 <span class="sy1"><<</span> <span class="st0">"'<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="sy2">++</span>i2<span class="sy4">;</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">"after incrementing i2, but not i1<span class="es1">\n</span>"</span>
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<span class="st0">"i1 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i1 <span class="sy1"><<</span> <span class="st0">"'<span class="es1">\n</span>"</span>
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<span class="st0">"i2 returns '"</span> <span class="sy1"><<</span> <span class="sy2">*</span>i2 <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></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">ss has 12 bytes; it holds "Hello, world"
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i1 returns 'a'
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i2 returns 'a'
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after incrementing i1, but not i2
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i1 returns 'b'
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i2 returns 'b'
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after incrementing i2, but not i1
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i1 returns 'c'
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i2 returns 'c'</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-ostreambuf_iterator.html"><span class="t-lines"><span>ostreambuf_iterator</span></span></a></div>
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</div>
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</td>
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<td>写入 <span class="t-lc"><a href="cpp-io-basic_streambuf.html">std::basic_streambuf</a></span> 的输出迭代器<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-istream_iterator.html"><span class="t-lines"><span>istream_iterator</span></span></a></div>
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</div>
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</td>
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<td>从 <span class="t-lc"><a href="cpp-io-basic_istream.html">std::basic_istream</a></span> 读取的输入迭代器<br />
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<span class="t-mark">(类模板)</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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