265 lines
16 KiB
HTML
265 lines
16 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::numpunct</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_locale_numpunct 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>numpunct</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-locale.html">locale</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-locale.html"><locale></a></code></div>
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</td>
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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="sy1">></span><br />
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<span class="kw1">class</span> numpunct<span class="sy4">;</span></span></div>
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<p>平面 <code>std::numpunct</code> 封装数值标点偏好。流 I/O 操作通过 <span class="t-lc"><a href="cpp-locale-num_get.html">std::num_get</a></span> 和 <span class="t-lc"><a href="cpp-locale-num_put.html">std::num_put</a></span> ,将用 <code>std::numpunct</code> 用于剖析数值输入,和格式化数值输出。</p>
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<p><code>std::numpunct</code> 所支持的数字拥有后述格式。此处 <code>digit</code> 表示 <code>fmtflags</code> 参数值所指定的基底集, <code>thousands-sep</code> 和 <code>decimal-point</code> 分别为 <span class="t-lc"><a href="cpp-locale-numpunct-thousands_sep.html">thousands_sep()</a></span> 和 <span class="t-lc"><a href="cpp-locale-numpunct-decimal_point.html">decimal_point()</a></span> 函数的结果。整数值格式如下:</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">integer ::= [sign] units
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sign ::= plusminus
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plusminus ::= '+' | '-'
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units ::= digits [thousands-sep units]
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digits ::= digit [digits]</pre></div>
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</div>
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<p><code>thousand-sep</code> 之间的数位( <code>digits</code> 的最大大小)由 <span class="t-lc"><a href="cpp-locale-numpunct-grouping.html">grouping()</a></span> 的结果指定。</p>
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<p>浮点值格式如下:</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">floatval ::= [sign] units [decimal-point [digits]] [e [sign] digits] |
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[sign] decimal-point digits [e [sign] digits]
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e ::= 'e' | 'E'</pre></div>
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</div>
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<div class="t-inheritance-diagram">
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<div class="center">
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<div class="noresize" style="height: 45px; width: 243px;"><map name="ImageMap_1_1518249413" id="ImageMap_1_1518249413">
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<area href="cpp-locale-locale-facet.html" shape="rect" coords="5,6,107,39" alt="cpp/locale/locale/facet" /></map><img alt="std-numpunct-inheritance.svg" src="std-numpunct-inheritance.svg" width="243" height="45" usemap="#ImageMap_1_1518249413" /></div>
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<div style="text-align:center;">
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<p><span style="font-size:0.7em; line-height:130%">继承图</span></p>
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</div>
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</div>
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<p>标准库提供二个孤立(独立于本地环境)的特化:</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-locale.html"><locale></a></code></div>
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</td>
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</tr>
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<tr class="t-dsc">
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">numpunct</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span></span></span></td>
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<td>提供 "C" 本地环境偏好的等价版本</td>
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</tr>
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<tr class="t-dsc">
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">numpunct</span><span class="sy1"><</span><span class="kw4">wchar_t</span><span class="sy1">></span></span></span></td>
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<td>提供 "C" 本地环境偏好的宽字符等价版本</td>
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</tr>
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</table>
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<p>另外, C++ 程序中构造的每个 locale 对象实现这些特化的其自身(本地环境限定)版本。</p>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>char_type</code></td>
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<td><code>charT</code></td>
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</tr>
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<tr class="t-dsc">
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<td><code>string_type</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>charT<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-locale-numpunct-numpunct.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 numpunct 平面<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><a href="cpp-locale-numpunct-~numpunct.html"><span class="t-lines"><span>(析构函数)</span></span></a></div>
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</div>
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</td>
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<td>析构 numpunct 平面<br />
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<span class="t-mark">(受保护成员函数)</span></td>
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</tr>
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<tr>
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<td colspan="2">
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<h5><span class="mw-headline" id=""></span></h5>
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</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-locale-numpunct-decimal_point.html"><span class="t-lines"><span>decimal_point</span></span></a></div>
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</div>
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</td>
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<td>调用 <code>do_decimal_point</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-locale-numpunct-thousands_sep.html"><span class="t-lines"><span>thousands_sep</span></span></a></div>
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</div>
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</td>
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<td>调用 <code>do_thousands_sep</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-locale-numpunct-grouping.html"><span class="t-lines"><span>grouping</span></span></a></div>
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</div>
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</td>
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<td>调用 <code>do_grouping</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-locale-numpunct-truefalsename.html"><span class="t-lines"><span>truename</span><span>falsename</span></span></a></div>
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</div>
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</td>
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<td>调用 <code>do_truename</code> 或 <code>do_falsename</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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</table>
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<h3><span class="mw-headline" id=".E5.8F.97.E4.BF.9D.E6.8A.A4.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">受保护成员函数</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-locale-numpunct-decimal_point.html"><span class="t-lines"><span>do_decimal_point</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>提供用作小数点的字符<br />
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<span class="t-mark">(虚受保护成员函数)</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-locale-numpunct-thousands_sep.html"><span class="t-lines"><span>do_thousands_sep</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>提供用作千分隔符的字符<br />
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<span class="t-mark">(虚受保护成员函数)</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-locale-numpunct-grouping.html"><span class="t-lines"><span>do_grouping</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>提供一对千分隔符之间的位数<br />
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<span class="t-mark">(虚受保护成员函数)</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-locale-numpunct-truefalsename.html"><span class="t-lines"><span>do_truename</span><span>do_falsename</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>提供用作布尔 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 名称的字符串<br />
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<span class="t-mark">(虚受保护成员函数)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.AF.B9.E8.B1.A1">成员对象</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><span class="t-lines"><span><span class="t-dsc-small">static std::locale::id</span> id</span></span></div>
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</div>
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</td>
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<td>locale 的 <i>id</i><br />
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<span class="t-mark">(公开成员对象)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<p>下列代码更改 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 的字符串表示</p>
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <locale></span>
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<span class="kw1">struct</span> french_bool <span class="sy4">:</span> std<span class="sy4">::</span><span class="me2">numpunct</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span> <span class="br0">{</span>
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string_type do_truename<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="kw1">return</span> <span class="st0">"oui"</span><span class="sy4">;</span> <span class="br0">}</span>
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string_type do_falsename<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span> <span class="kw1">return</span> <span class="st0">"non"</span><span class="sy4">;</span> <span class="br0">}</span>
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<span class="br0">}</span><span class="sy4">;</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-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"default locale: "</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1764">std::<span class="me2">boolalpha</span></span></a> <span class="sy1"><<</span> <span class="kw2">true</span> <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> <span class="kw2">false</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</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="me1">imbue</span><span class="br0">(</span><a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a><span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>.<span class="me1">getloc</span><span class="br0">(</span><span class="br0">)</span>, new french_bool<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">"locale with modified numpunct: "</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1764">std::<span class="me2">boolalpha</span></span></a> <span class="sy1"><<</span> <span class="kw2">true</span> <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> <span class="kw2">false</span> <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">default locale: true, false
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locale with modified numpunct: oui, non</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-locale-numpunct_byname.html"><span class="t-lines"><span>numpunct_byname</span></span></a></div>
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</div>
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</td>
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<td>为具名 locale 创建 numpunct 平面<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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