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hustoj/web/cppreference-zh/chmhelp/cpp-locale-has_facet.html
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>has_facet</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-locale.html">locale</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-locale.html">&lt;locale&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> Facet <span class="sy1">&gt;</span><br />
<span class="kw4">bool</span> has_facet<span class="br0">(</span> <span class="kw4">const</span> locale<span class="sy3">&amp;</span> loc <span class="br0">)</span> <span class="kw1">throw</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 &#21069;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1">&lt;</span> <span class="kw1">class</span> Facet <span class="sy1">&gt;</span><br />
<span class="kw4">bool</span> has_facet<span class="br0">(</span> <span class="kw4">const</span> locale<span class="sy3">&amp;</span> loc <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p>&#26816;&#26597; locale <code>loc</code> &#26159;&#21542;&#23454;&#35013;&#24179;&#38754; <code>Facet</code> &#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>loc</td>
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<td>&#35201;&#26597;&#35810;&#30340; locale &#23545;&#35937;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#33509;&#24403;&#21069; locale <code>loc</code> &#20013;&#23433;&#35013;&#20102;&#24179;&#38754; <code>Facet</code> &#21017;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#65292;&#21542;&#21017;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> &#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;locale&gt;</span>
<span class="co1">// &#26368;&#23567;&#23450;&#21046;&#24179;&#38754;</span>
<span class="kw1">struct</span> myfacet <span class="sy4">:</span> <span class="kw1">public</span> <a href="cpp-locale-locale-facet.html"><span class="kw1896">std::<span class="me2">locale</span><span class="sy4">::</span><span class="me2">facet</span></span></a> <span class="br0">{</span>
<span class="kw4">static</span> <a href="cpp-locale-locale-id.html"><span class="kw1895">std::<span class="me2">locale</span><span class="sy4">::</span><span class="me2">id</span></span></a> id<span class="sy4">;</span>
<span class="br0">}</span><span class="sy4">;</span>
<a href="cpp-locale-locale-id.html"><span class="kw1895">std::<span class="me2">locale</span><span class="sy4">::</span><span class="me2">id</span></span></a> myfacet<span class="sy4">::</span><span class="me2">id</span><span class="sy4">;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="co1">// loc &#26159;&#21152;&#19978; myfacet &#30340; &quot;C&quot; &#26412;&#22320;&#29615;&#22659;</span>
<a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a> loc<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">locale</span><span class="sy4">::</span><span class="me2">classic</span><span class="br0">(</span><span class="br0">)</span>, new myfacet<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1764">std::<span class="me2">boolalpha</span></span></a>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Can loc classify chars? &quot;</span>
<span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">has_facet</span><span class="sy1">&lt;</span><a href="cpp-locale-ctype.html"><span class="kw1937">std::<span class="me2">ctype</span></span></a><span class="sy1">&lt;</span><span class="kw4">char</span><span class="sy1">&gt;&gt;</span><span class="br0">(</span>loc<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Can loc classify char32_t? &quot;</span>
<span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">has_facet</span><span class="sy1">&lt;</span><a href="cpp-locale-ctype.html"><span class="kw1937">std::<span class="me2">ctype</span></span></a><span class="sy1">&lt;</span><span class="kw4">char32_t</span><span class="sy1">&gt;&gt;</span><span class="br0">(</span>loc<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot;Does loc implement myfacet? &quot;</span>
<span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">has_facet</span><span class="sy1">&lt;</span>myfacet<span class="sy1">&gt;</span><span class="br0">(</span>loc<span class="br0">)</span> <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">Can loc classify chars? true
Can loc classify char32_t? false
Does loc implement myfacet? true</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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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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<td>&#29992;&#20197;&#23553;&#35013;&#25991;&#21270;&#24046;&#24322;&#30340;&#22810;&#24577;&#21051;&#38754;&#30340;&#38598;&#21512;<br />
<span class="t-mark">(&#31867;)</span></td>
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<div><a href="cpp-locale-use_facet.html"><span class="t-lines"><span>use_facet</span></span></a></div>
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<td>&#20174;&#26412;&#22320;&#29615;&#22659;&#33719;&#24471;&#19968;&#20010;&#21051;&#38754;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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