122 lines
14 KiB
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122 lines
14 KiB
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<title>std::setlocale</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_locale_setlocale skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>setlocale</h1>
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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>定义于头文件 <code><a href="cpp-header-clocale.html"><clocale></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span><span class="sy2">*</span> setlocale<span class="br0">(</span> <span class="kw4">int</span> category, <span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> locale<span class="br0">)</span><span class="sy4">;</span></span></div>
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<p><code>setlocale</code> 函数安装指定的系统本地环境或其一部分，作为新的 C 本地环境。修改保持效果，并影响所有关乎本地环境的 C 库函数执行，到下次调用 <code>setlocale</code> 为止。若 <code>locale</code> 为空指针，则 <code>setlocale</code> 查询当前 C 本地环境而不修改它。</p>
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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>category</td>
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<td>-</td>
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<td>本地环境类别标识符， <a href="cpp-locale-LC_categories.html">LC_xxx</a> 宏之一。可为 0 。</td>
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<tr class="t-par">
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<td>locale</td>
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<td>-</td>
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<td>系统限定的本地环境标识符。对于用户偏好的本地环境为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">""</span></span></span> ，对于最小本地环境为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">"C"</span></span></span> 。</td>
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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>指向窄空终止字符串的指针，它表示应用更改后的 C 本地环境，若存在。或在失败时为空指针。</p>
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<p>返回字符串的副本和到 <code>std::setlocale</code> 的此调用中所用的类别，可在程序的后面用来恢复本地环境到此调用结束时的状态。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>程序启动过程中，运行任何用户代码前会执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">setlocale</span><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1992">LC_ALL</span></a>, <span class="st0">"C"</span><span class="br0">)</span><span class="sy4">;</span></span></span> 的等价代码。</p>
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<p>尽管返回类型为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span><span class="sy2">*</span></span></span> ，修改被指向的字符是未定义行为。</p>
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<p><code>setlocale</code> 修改影响本地环境依赖函数的全局状态，故从一个线程调用它，而另一线程同时执行任何下列函数是未定义行为： <span class="t-lc"><a href="cpp-io-c-fprintf.html">std::fprintf</a></span> 、 <span class="t-lc">std::isprint</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswdigit.html">std::iswdigit</a></span> 、 <span class="t-lc"><a href="cpp-locale-localeconv.html">std::localeconv</a></span> 、 <span class="t-lc">std::tolower</span> 、 <span class="t-lc"><a href="cpp-io-c-fscanf.html">std::fscanf</a></span> 、 <span class="t-lc">std::ispunct</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswgraph.html">std::iswgraph</a></span> 、 <span class="t-lc"><a href="cpp-string-multibyte-mblen.html">std::mblen</a></span> 、 <span class="t-lc">std::toupper</span> 、 <span class="t-lc">std::isalnum</span> 、 <span class="t-lc">std::isspace</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswlower.html">std::iswlower</a></span> 、 <span class="t-lc"><a href="cpp-string-multibyte-mbstowcs.html">std::mbstowcs</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-towlower.html">std::towlower</a></span> 、 <span class="t-lc">std::isalpha</span> 、 <span class="t-lc">std::isupper</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswprint.html">std::iswprint</a></span> 、 <span class="t-lc"><a href="cpp-string-multibyte-mbtowc.html">std::mbtowc</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-towupper.html">std::towupper</a></span> 、 <span class="t-lc">std::isblank</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswalnum.html">std::iswalnum</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-iswpunct.html">std::iswpunct</a></span> 、 <span class="t-lc"><strong class="selflink">std::setlocale</strong></span> 、 <span class="t-lc"><a href="cpp-string-wide-wcscoll.html">std::wcscoll</a></span> 、 <span class="t-lc">std::iscntrl</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswalpha.html">std::iswalpha</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-iswspace.html">std::iswspace</a></span> 、 <span class="t-lc"><a href="cpp-string-byte-strcoll.html">std::strcoll</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-wcstof.html">std::wcstod</a></span> 、 <span class="t-lc">std::isdigit</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswblank.html">std::iswblank</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-iswupper.html">std::iswupper</a></span> 、 <span class="t-lc"><a href="cpp-string-byte-strerror.html">std::strerror</a></span> 、 <span class="t-lc"><a href="cpp-string-multibyte-wcstombs.html">std::wcstombs</a></span> 、 <span class="t-lc">std::isgraph</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswcntrl.html">std::iswcntrl</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-iswxdigit.html">std::iswxdigit</a></span> 、 <span class="t-lc"><a href="cpp-string-byte-strtof.html">std::strtod</a></span> 、 <span class="t-lc"><a href="cpp-string-wide-wcsxfrm.html">std::wcsxfrm</a></span> 、 <span class="t-lc">std::islower</span> 、 <span class="t-lc"><a href="cpp-string-wide-iswctype.html">std::iswctype</a></span> 、 <span class="t-lc">std::isxdigit</span> 。</p>
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<p>POSIX 亦定义名为 "POSIX" 的本地环境，它始终可访问，并准确等于默认的最小 "C" 本地环境。</p>
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<p>POSIX 亦指定后继的 setlocale 调用可以非法化返回的指针，而不仅是被指向的字符串内容。</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 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 <cstdio></span>
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<span class="co2">#include <clocale></span>
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<span class="co2">#include <ctime></span>
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<span class="co2">#include <cwchar></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">// C 本地环境将为启用 UTF-8 的英文；</span>
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<span class="co1">// 小数点将为德文</span>
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<span class="co1">// 日期和时间格式将为日文</span>
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std<span class="sy4">::</span><span class="me2">setlocale</span><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1992">LC_ALL</span></a>, <span class="st0">"en_US.UTF-8"</span><span class="br0">)</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">setlocale</span><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1996">LC_NUMERIC</span></a>, <span class="st0">"de_DE.UTF-8"</span><span class="br0">)</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">setlocale</span><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1997">LC_TIME</span></a>, <span class="st0">"ja_JP.UTF-8"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">wchar_t</span> str<span class="br0">[</span><span class="nu0">100</span><span class="br0">]</span><span class="sy4">;</span>
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<a href="cpp-chrono-c-time_t.html"><span class="kw1024">std::<span class="me2">time_t</span></span></a> t <span class="sy1">=</span> <a href="cpp-chrono-c-time.html"><span class="kw1011">std::<span class="me2">time</span></span></a><span class="br0">(</span><a href="cpp-types-NULL.html"><span class="kw103">NULL</span></a><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-chrono-c-wcsftime.html"><span class="kw1018">std::<span class="me2">wcsftime</span></span></a><span class="br0">(</span>str, <span class="nu0">100</span>, L<span class="st0">"%A %c"</span>, <a href="cpp-chrono-c-localtime.html"><span class="kw1020">std::<span class="me2">localtime</span></span></a><span class="br0">(</span><span class="sy3">&</span>t<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-c-fwprintf.html"><span class="kw1859">std::<span class="me2">wprintf</span></span></a><span class="br0">(</span>L<span class="st0">"Number: %.2f<span class="es1">\n</span>Date: %Ls<span class="es1">\n</span>"</span>, <span class="nu16">3.14</span>, str<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">Number: 3,14
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Date: 月曜日 2011年12月19日 18時04分40秒</pre></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 class="t-dsc-member-div">
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<div><a href="cpp-locale-LC_categories.html"><span class="t-lines"><span>LC_ALL</span><span>LC_COLLATE</span><span>LC_CTYPE</span><span>LC_MONETARY</span><span>LC_NUMERIC</span><span>LC_TIME</span></span></a></div>
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</td>
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<td><span class="t-lc"><strong class="selflink">std::setlocale</strong></span> 所用的本地环境类别<br />
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<span class="t-mark">(宏常量)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-locale-locale.html"><span class="t-lines"><span>locale</span></span></a></div>
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</div>
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</td>
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<td>用以封装文化差异的多态刻面的集合<br />
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<span class="t-mark">(类)</span></td>
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