109 lines
9.7 KiB
HTML
109 lines
9.7 KiB
HTML
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<title>std::locale::operator()</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_locale_locale_operator 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::locale::</span>operator()</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-locale.html">locale</a>‎ | <a href="cpp-locale-locale.html">locale</a></span></div>
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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> Alloc <span class="sy1">></span><br /></span>
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<p><span class="kw4">bool</span> operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> <span class="kw4">const</span> basic_string<span class="sy1"><</span>CharT,Traits,Alloc<span class="sy1">></span><span class="sy3">&</span> s1,<br /></p>
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<span class="kw4">const</span> basic_string<span class="sy1"><</span>CharT,Traits,Alloc<span class="sy1">></span><span class="sy3">&</span> s2<span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></div>
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<p>按照此 locale 的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-locale-collate.html"><span class="kw1943">std::<span class="me2">collate</span></span></a><span class="sy1"><</span>charT<span class="sy1">></span></span></span> 平面所定义的比较规则，比较二个 string 参数 <code>s1</code> 与 <code>s2</code> 。此运算符允许以任何拥有 collate 平面的 locale 对象为标准算法（如 <span class="t-lc"><a href="cpp-algorithm-sort.html">std::sort</a></span> ）和有序容器（ <span class="t-lc"><a href="cpp-container-set.html">std::set</a></span> ）中的二元谓词。</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>s1</td>
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<td>-</td>
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<td>要比较的第一字符串</td>
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</tr>
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<tr class="t-par">
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<td>s2</td>
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<td>-</td>
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<td>要比较的第二字符串</td>
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</tr>
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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 <code>s1</code> 按字典序小于 <code>s2</code> 则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，否则为 <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="kw1">class</span> Traits, <span class="kw1">class</span> Alloc <span class="sy1">></span>
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<span class="kw4">bool</span> operator<span class="br0">(</span><span class="br0">)</span><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,Alloc<span class="sy1">></span><span class="sy3">&</span> s1,
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<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,Alloc<span class="sy1">></span><span class="sy3">&</span> s2<span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span>
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<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-collate.html"><span class="kw1943">std::<span class="me2">collate</span></span></a><span class="sy1"><</span>CharT<span class="sy1">>></span><span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span>.<span class="me1">compare</span><span class="br0">(</span>
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s1.<span class="me1">data</span><span class="br0">(</span><span class="br0">)</span>, s1.<span class="me1">data</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> s1.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span>,
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s2.<span class="me1">data</span><span class="br0">(</span><span class="br0">)</span>, s2.<span class="me1">data</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> s2.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span> <span class="sy1"><</span> <span class="nu0">0</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>string 的 vector 能以 locale 对象为比较器，按照非默认的本地环境排序：</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 <locale></span>
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<span class="co2">#include <algorithm></span>
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<span class="co2">#include <vector></span>
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<span class="co2">#include <string></span>
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<span class="co2">#include <cassert></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-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1232">std::<span class="me2">wstring</span></span></a><span class="sy1">></span> v <span class="sy1">=</span> <span class="br0">{</span>L<span class="st0">"жил"</span>, L<span class="st0">"был"</span>, L<span class="st0">"кот"</span><span class="br0">}</span><span class="sy4">;</span>
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<a href="cpp-algorithm-sort.html"><span class="kw1618">std::<span class="me2">sort</span></span></a><span class="br0">(</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">end</span><span class="br0">(</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">"ru_RU.UTF8"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>v<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span> <span class="sy1">==</span> L<span class="st0">"был"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>v<span class="br0">[</span><span class="nu0">1</span><span class="br0">]</span> <span class="sy1">==</span> L<span class="st0">"жил"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-error-assert.html"><span class="kw774">assert</span></a><span class="br0">(</span>v<span class="br0">[</span><span class="nu0">2</span><span class="br0">]</span> <span class="sy1">==</span> L<span class="st0">"кот"</span><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=".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-collate.html"><span class="t-lines"><span>collate</span></span></a></div>
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</div>
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</td>
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<td>定义字典序比较和字符串的散列<br />
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<span class="t-mark">(类模板)</span></td>
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<div class="visualClear"></div>
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