126 lines
7.9 KiB
HTML
126 lines
7.9 KiB
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::islower(std::locale)</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_locale_islower 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>islower<span style="font-size:0.7em; line-height:130%">(std::locale)</span></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-locale.html"><locale></a></code></div>
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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="kw4">bool</span> islower<span class="br0">(</span> charT ch, <span class="kw4">const</span> locale<span class="sy3">&</span> loc <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>检查给定字符是否为给定 locale 的 <span class="t-lc"><a href="cpp-locale-ctype.html">std::ctype</a></span> 平面分类为小写字母字符。</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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<td>ch</td>
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<td>-</td>
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<td>字符</td>
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<tr class="t-par">
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<td>loc</td>
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<td>-</td>
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<td>本地环境</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>若给定字符被分类为小写则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，否则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
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<div class="cpp source-cpp">
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<pre class="de1"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> charT <span class="sy1">></span>
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<span class="kw4">bool</span> islower<span class="br0">(</span> charT ch, <span class="kw4">const</span> <a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a><span class="sy3">&</span> loc <span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">return</span> <a href="cpp-locale-use_facet.html"><span class="kw1897">std::<span class="me2">use_facet</span></span></a><span class="sy1"><</span><a href="cpp-locale-ctype.html"><span class="kw1938">std::<span class="me2">ctype</span></span></a><span class="sy1"><</span>charT<span class="sy1">>></span><span class="br0">(</span>loc<span class="br0">)</span>.<span class="me1">is</span><span class="br0">(</span><a href="cpp-locale-ctype_base.html"><span class="kw1907">std::<span class="me2">ctype_base</span><span class="sy4">::</span><span class="me2">lower</span></span></a>, ch<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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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>演示用不同本地环境使用 <code>islower()</code> （ OS 特定）。</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="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">const</span> <span class="kw4">wchar_t</span> c <span class="sy1">=</span> L<span class="st0">'<span class="es3">\u03c0</span>'</span><span class="sy4">;</span> <span class="co1">// 希腊文小写字母 pi</span>
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<a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a> loc1<span class="br0">(</span><span class="st0">"C"</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">"islower('π', C locale) returned "</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> std<span class="sy4">::</span><span class="me2">islower</span><span class="br0">(</span>c, loc1<span class="br0">)</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-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a> loc2<span class="br0">(</span><span class="st0">"en_US.UTF8"</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">"islower('π', Unicode locale) returned "</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> std<span class="sy4">::</span><span class="me2">islower</span><span class="br0">(</span>c, loc2<span class="br0">)</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>可能的输出：</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">islower('π', C locale) returned false
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islower('π', Unicode locale) returned true</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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<table class="t-dsc-begin">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-byte-islower.html"><span class="t-lines"><span>islower</span></span></a></div>
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</div>
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</td>
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<td>检查字符是否为小写<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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<div class="t-dsc-member-div">
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<div><a href="cpp-string-wide-iswlower.html"><span class="t-lines"><span>iswlower</span></span></a></div>
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</div>
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</td>
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<td>检查宽字符是否为小写<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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