164 lines
19 KiB
HTML
164 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::quoted</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_io_manip_quoted 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>quoted</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-io.html">io</a>‎ | <a href="cpp-io-manip.html">manip</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-iomanip.html"><iomanip></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>
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<tr class="t-dcl t-since-cxx14">
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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="sy1">></span><br /></span>
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<p><span class="coMULTI">/*unspecified*/</span> quoted<span class="br0">(</span><span class="kw4">const</span> CharT<span class="sy2">*</span> s,<br /></p>
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CharT delim<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'"'</span><span class="br0">)</span>, CharT escape<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'<span class="es1">\\</span>'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx14">
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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="kw1">class</span> Allocator <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/*unspecified*/</span> quoted<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Allocator<span class="sy1">></span><span class="sy3">&</span> s,<br /></p>
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CharT delim<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'"'</span><span class="br0">)</span>, CharT escape<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'<span class="es1">\\</span>'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx17">
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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><br /></span>
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<p><span class="coMULTI">/*unspecified*/</span> quoted<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span> s,<br /></p>
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CharT delim<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'"'</span><span class="br0">)</span>, CharT escape<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'<span class="es1">\\</span>'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx14">
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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="kw1">class</span> Allocator <span class="sy1">></span><br /></span>
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<p><span class="coMULTI">/*unspecified*/</span> quoted<span class="br0">(</span><a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT, Traits, Allocator<span class="sy1">></span><span class="sy3">&</span> s,<br /></p>
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CharT delim<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'"'</span><span class="br0">)</span>, CharT escape<span class="sy1">=</span>CharT<span class="br0">(</span><span class="st0">'<span class="es1">\\</span>'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>允许插入或释出带引号字符串，例如在 CSV 或 XML 中找到者。</p>
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<p>用于表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">out <span class="sy1"><<</span> quoted<span class="br0">(</span>s, delim, escape<span class="br0">)</span></span></span> ，其中 <code>out</code> 为拥有等于 <code>CharT</code> 的 <code>char_type</code> 的输出流，对于重载 2-4 ，还拥有等于 <code>Traits</code> 的 <code>traits_type</code> 时，表现为<a href="cpp-named_req-FormattedOutputFunction.html"><span style="font-style:italic">有格式输出函数</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(FormattedOutputFunction)</span></a> ，它插入以如下方式构造的字符序列 <code>seq</code> 到 <span class="t-c"><span class="mw-geshi cpp source-cpp">out</span></span> ：</p>
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<div class="t-li1"><span class="t-li">a)</span> 首先，添加字符 <code>delim</code> 到序列</div>
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<div class="t-li1"><span class="t-li">b)</span> 然后添加每个来自 <code>s</code> 的字符，除了若下个要输出的字符等于 <code>delim</code> 或等于 <code>escape</code> （以流的 <code>traits_type::eq</code> 确定），则首先后附 <code>escape</code> 的额外副本</div>
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<div class="t-li1"><span class="t-li">c)</span> 最后，后附 <code>delim</code> 多一次到 <code>seq</code></div>
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<p>然后，若 <code>seq.size() < out.width()</code> ，则添加 <code>out.width()-seq.size()</code> 个填充字符 <code>out.fill()</code> 副本到序列的末尾（若 <code>out.flags()</code> 中设置了 <code>ios_base::left</code> ）或到序列的起始（所有其他情况下）。</p>
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<p>最后，如同以调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">out.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>sputn<span class="br0">(</span>seq, n<span class="br0">)</span></span></span> 输出来自每个结果序列的字符，其中 <span class="t-c"><span class="mw-geshi cpp source-cpp">n<span class="sy1">=</span><a href="cpp-algorithm-max.html"><span class="kw1640">std::<span class="me2">max</span></span></a><span class="br0">(</span>out.<span class="me1">width</span><span class="br0">(</span><span class="br0">)</span>, seq.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> ，并调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">out.<span class="me1">width</span><span class="br0">(</span><span class="nu0">0</span><span class="br0">)</span></span></span> 取消 <span class="t-lc"><a href="cpp-io-manip-setw.html">std::setw</a></span> 的效果，若存在。</p>
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<div class="t-li1"><span class="t-li">4)</span> 用于表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">in <span class="sy1">>></span> quoted<span class="br0">(</span>s, delim, escape<span class="br0">)</span></span></span> 中，其中 <code>in</code> 是拥有等于 <code>CharT</code> 的 <code>char_type</code> 和等于 <code>Traits</code> 的 <code>traits_type</code> 输入流时，用 <span class="t-lc"><a href="cpp-io-basic_istream-operator_gtgt.html">std::basic_istream::operator>></a></span> 按照下列规则从 <span class="t-c"><span class="mw-geshi cpp source-cpp">in</span></span> 释出字符：</div>
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<div class="t-li2"><span class="t-li">a)</span> 若首个释出的字符不等于 <code>delim</code> （以流的 <code>traits_type::eq</code> 确定），则简单地进行 <span class="t-c"><span class="mw-geshi cpp source-cpp">in <span class="sy1">>></span> s</span></span> 。</div>
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<div class="t-li2"><span class="t-li">b)</span> 否则（若首字符是分隔符）：</div>
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<div class="t-li3"><span class="t-li">1)</span> 关闭输入流上的 <span class="t-lc">skipws</span> 标志</div>
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<div class="t-li3"><span class="t-li">2)</span> 通过调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">s.<span class="me1">clear</span><span class="br0">(</span><span class="br0">)</span></span></span> 清空目标字符串</div>
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<div class="t-li3"><span class="t-li">3)</span> 从 <code>in</code> 释出字符并后附字符到 <code>s</code> ，除了凡在释出 <code>escape</code> 字符时，忽略该字符并后附下个字符到 <code>s</code> 。 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy3">!</span>in<span class="sy1">==</span><span class="kw2">true</span></span></span> 时或找到未转义的 <code>delim</code> 字符时释出停止。</div>
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<div class="t-li3"><span class="t-li">4)</span> 舍弃最终（未转义）的 <code>delim</code> 字符。</div>
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<div class="t-li3"><span class="t-li">5)</span> 恢复输入流上的 <span class="t-lc">skipws</span> 标志为其原值。</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>s</td>
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<td>-</td>
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<td>要插入或释出的字符串</td>
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</tr>
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<tr class="t-par">
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<td>delim</td>
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<td>-</td>
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<td>用作分隔符的字符，默认为 <code>"</code></td>
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</tr>
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<tr class="t-par">
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<td>escape</td>
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<td>-</td>
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<td>用作转义字符的字符，默认为 <code>\</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>返回未指定类型对象，使得上述行为发生。</p>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>若 <code>operator>></code> 或 <code>operator<<</code> 抛出则抛出 <span class="t-lc"><a href="cpp-io-ios_base-failure.html">std::ios_base::failure</a></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 <iostream></span>
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<span class="co2">#include <iomanip></span>
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<span class="co2">#include <sstream></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-io-basic_stringstream.html"><span class="kw1737">std::<span class="me2">stringstream</span></span></a> ss<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> in <span class="sy1">=</span> <span class="st0">"String with spaces, and embedded <span class="es1">\"</span>quotes<span class="es1">\"</span> too"</span><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> out<span class="sy4">;</span>
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<span class="kw4">auto</span> show <span class="sy1">=</span> <span class="br0">[</span><span class="sy3">&</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> what<span class="br0">)</span> <span class="br0">{</span>
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<span class="sy3">&</span>what <span class="sy1">==</span> <span class="sy3">&</span>in
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<span class="sy4">?</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"read in ["</span> <span class="sy1"><<</span> in <span class="sy1"><<</span> <span class="st0">"]<span class="es1">\n</span>"</span>
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<span class="sy1"><<</span> <span class="st0">"stored as ["</span> <span class="sy1"><<</span> ss.<span class="me1">str</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"]<span class="es1">\n</span>"</span>
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<span class="sy4">:</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"written out ["</span> <span class="sy1"><<</span> out <span class="sy1"><<</span> <span class="st0">"]<span class="es1">\n</span><span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span><span class="sy4">;</span>
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ss <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">quoted</span><span class="br0">(</span>in<span class="br0">)</span><span class="sy4">;</span>
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show<span class="br0">(</span>in<span class="br0">)</span><span class="sy4">;</span>
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ss <span class="sy1">>></span> std<span class="sy4">::</span><span class="me2">quoted</span><span class="br0">(</span>out<span class="br0">)</span><span class="sy4">;</span>
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show<span class="br0">(</span>out<span class="br0">)</span><span class="sy4">;</span>
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ss.<span class="me1">str</span><span class="br0">(</span><span class="st0">""</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// clear the stream buffer</span>
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in <span class="sy1">=</span> <span class="st0">"String with spaces, and embedded $quotes$ too"</span><span class="sy4">;</span>
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<span class="kw4">const</span> <span class="kw4">char</span> delim <span class="br0">{</span><span class="st0">'$'</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="kw4">const</span> <span class="kw4">char</span> escape <span class="br0">{</span><span class="st0">'%'</span><span class="br0">}</span><span class="sy4">;</span>
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ss <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">quoted</span><span class="br0">(</span>in, delim, escape<span class="br0">)</span><span class="sy4">;</span>
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show<span class="br0">(</span>in<span class="br0">)</span><span class="sy4">;</span>
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ss <span class="sy1">>></span> std<span class="sy4">::</span><span class="me2">quoted</span><span class="br0">(</span>out, delim, escape<span class="br0">)</span><span class="sy4">;</span>
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show<span class="br0">(</span>out<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">read in [String with spaces, and embedded "quotes" too]
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stored as ["String with spaces, and embedded \"quotes\" too"]
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written out [String with spaces, and embedded "quotes" too]
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read in [String with spaces, and embedded $quotes$ too]
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stored as [$String with spaces, and embedded %$quotes%$ too$]
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written out [String with spaces, and embedded $quotes$ too]</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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</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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