241 lines
16 KiB
HTML
241 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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<title>std::num_put</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_locale_num_put 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>num_put</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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<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></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><br /></span>
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<p> <span class="kw1">class</span> CharT,<br />
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<span class="kw1">class</span> OutputIt <span class="sy1">=</span> <a href="cpp-iterator-ostreambuf_iterator.html"><span class="kw671">std::<span class="me2">ostreambuf_iterator</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> num_put<span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
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<td class="t-dcl-nopad"></td>
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<p>类 <code>std::num_put</code> 封装格式化数值为字符串的规则。具体而言支持 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">long</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">double</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span><span class="sy2">*</span></span></span> 类型和所有能隐式转换到它们的类型（例如 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">float</span></span></span> ）。标准格式化输出运算符（如 <span class="t-c"><span class="mw-geshi cpp source-cpp">cout <span class="sy1"><<</span> n<span class="sy4">;</span></span></span> ）用 I/O 流的 locale 的 <code>std::num_put</code> 平面生成数字的文本表示。</p>
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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: 277px;"><map name="ImageMap_1_1999382184" id="ImageMap_1_1999382184">
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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-num put-inheritance.svg" src="std-num_put-inheritance.svg" width="277" height="45" usemap="#ImageMap_1_1999382184" /></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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<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>OutputIt</code> 必须满足<a href="cpp-named_req-OutputIterator.html"><span style="font-style:italic">老式输出迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyOutputIterator)</span></a> 的要求。</td>
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</tr>
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</table>
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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>标准库提供二个孤立（独立于本地环境）的全特化和二个部分特化：</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">num_put</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span></span></span></td>
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<td>创建数的窄字符串表示</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">num_put</span><span class="sy1"><</span><span class="kw4">wchar_t</span><span class="sy1">></span></span></span></td>
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<td>创建数的宽字符串表示</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">num_put</span><span class="sy1"><</span><span class="kw4">char</span>, OutputIt<span class="sy1">></span></span></span></td>
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<td>用定制输出迭代器创建数的窄字符串表示</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">num_put</span><span class="sy1"><</span><span class="kw4">wchar_t</span>, OutputIt<span class="sy1">></span></span></span></td>
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<td>用定制输出迭代器创建数的宽字符串表示</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 对象都实装这些特化的其自身（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 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>iter_type</code></td>
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<td><code>OutputIt</code></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-locale-num_put-num_put.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 num_put 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-num_put-~num_put.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>销毁 num_put 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 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-num_put-put.html"><span class="t-lines"><span>put</span></span></a></div>
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</div>
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</td>
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<td>调用 <code>do_put</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-num_put-put.html"><span class="t-lines"><span>do_put</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>格式化数字并写入到输出流<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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<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="co2">#include <string></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="kw4">double</span> n <span class="sy1">=</span> <span class="nu16">1234567.89</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><span class="st0">"de_DE"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Direct conversion to string:<span class="es1">\n</span>"</span>
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<span class="sy1"><<</span> <a href="cpp-string-basic_string-to_string.html"><span class="kw1265">std::<span class="me2">to_string</span></span></a><span class="br0">(</span>n<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"Output using a german locale:<span class="es1">\n</span>"</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-fixed.html"><span class="kw1784">std::<span class="me2">fixed</span></span></a> <span class="sy1"><<</span> n <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"Output using an american locale:<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="co1">// 直接使用平面</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><span class="st0">"en_US.UTF-8"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">auto</span><span class="sy3">&</span> f <span class="sy1">=</span> <a href="cpp-locale-use_facet.html"><span class="kw1897">std::<span class="me2">use_facet</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">num_put</span><span class="sy1"><</span><span class="kw4">char</span><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="me1">getloc</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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f.<span class="me1">put</span><span class="br0">(</span><a href="cpp-iterator-ostreambuf_iterator.html"><span class="kw671">std::<span class="me2">ostreambuf_iterator</span></span></a><span class="sy1"><</span><span class="kw4">char</span><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="br0">)</span>, <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>, <span class="st0">' '</span>, n<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">'<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">Direct conversion to string:
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1234567.890000
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Output using a german locale:
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1.234.567,890000
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Output using an american locale:
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1,234,567.890000</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.html"><span class="t-lines"><span>numpunct</span></span></a></div>
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</div>
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</td>
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<td>定义数值标点规则<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-locale-num_get.html"><span class="t-lines"><span>num_get</span></span></a></div>
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</div>
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</td>
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<td>从输入字符序列中解析数字值<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-string-basic_string-to_string.html"><span class="t-lines"><span>to_string</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>转换整数或浮点值为 <code>string</code><br />
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<span class="t-mark">(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-string-basic_string-to_wstring.html"><span class="t-lines"><span>to_wstring</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>转换整数或浮点值为 <code>wstring</code><br />
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<span class="t-mark">(函数)</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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