144 lines
8.6 KiB
HTML
144 lines
8.6 KiB
HTML
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<title>std::wmemchr</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_wide_wmemchr 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>wmemchr</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-string.html">string</a>‎ | <a href="cpp-string-wide.html">wide</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-cwchar.html"><cwchar></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> wmemchr<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> ptr, <span class="kw4">wchar_t</span> ch, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> count <span class="br0">)</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp"> <span class="kw4">wchar_t</span><span class="sy2">*</span> wmemchr<span class="br0">(</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> ptr, <span class="kw4">wchar_t</span> ch, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> count <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>于 <code>ptr</code> 所指向的宽字符数组的首 <code>count</code> 个宽字符中，定位宽字符 <code>ch</code> 的首次出现。</p>
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<p>若 <code>count</code> 为零，则函数返回空指针。</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>ptr</td>
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<td>-</td>
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<td>指向要检验的宽字符数组的指针</td>
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<tr class="t-par">
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<td>ch</td>
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<td>-</td>
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<td>要搜索的宽字符</td>
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</tr>
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<tr class="t-par">
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<td>count</td>
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<td>-</td>
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<td>要检验的宽字符数</td>
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</tr>
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</table>
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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>指向宽字符位置的指针，或若找不到这种字符则为空指针。</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="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <cwchar></span>
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<span class="co2">#include <clocale></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> str<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> L<span class="st0">"诺不轻信，故人不负我<span class="es5">\0</span>诺不轻许，故我不负人。"</span><span class="sy4">;</span>
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<span class="kw4">wchar_t</span> target <span class="sy1">=</span> L<span class="st0">'许'</span><span class="sy4">;</span>
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<span class="kw4">const</span> <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> sz <span class="sy1">=</span> sizeof str <span class="sy2">/</span> sizeof <span class="sy2">*</span>str<span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> result <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">wmemchr</span><span class="br0">(</span>str, target, sz<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-locale-setlocale.html"><span class="kw1989">std::<span class="me2">setlocale</span></span></a><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1992">LC_ALL</span></a>, <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">wcout</span></span></a>.<span class="me1">imbue</span><span class="br0">(</span><a href="cpp-locale-locale.html"><span class="kw1893">std::<span class="me2">locale</span></span></a><span class="br0">(</span><span class="st0">"en_US.utf8"</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">wcout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Found '"</span> <span class="sy1"><<</span> target
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<span class="sy1"><<</span> <span class="st0">"' at position "</span> <span class="sy1"><<</span> result <span class="sy2">-</span> str <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>
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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">Found '许' at position 14</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-memchr.html"><span class="t-lines"><span>memchr</span></span></a></div>
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</div>
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</td>
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<td>在数组中搜索字符的首次出现<br />
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<span class="t-mark">(函数)</span></td>
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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-byte-strchr.html"><span class="t-lines"><span>strchr</span></span></a></div>
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</div>
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</td>
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<td>寻找字符的首次出现<br />
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<span class="t-mark">(函数)</span></td>
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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-wide-wcschr.html"><span class="t-lines"><span>wcschr</span></span></a></div>
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</div>
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</td>
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<td>寻找宽字符串中宽字符的首次出现<br />
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<span class="t-mark">(函数)</span></td>
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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-algorithm-find.html"><span class="t-lines"><span>find</span><span>find_if</span><span>find_if_not</span></span></a></div>
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<div><span class="t-lines"><span></span><span></span><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>寻找首个满足特定判别标准的元素<br />
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<span class="t-mark">(函数模板)</span></td>
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</table>
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</div>
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<div class="visualClear"></div>
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