129 lines
9.3 KiB
HTML
129 lines
9.3 KiB
HTML
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<title>std::wmemcpy</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_wide_wmemcpy 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>wmemcpy</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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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span><span class="sy2">*</span> wmemcpy<span class="br0">(</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> dest, <span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> src, <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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<td class="t-dcl-nopad"></td>
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<td></td>
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<p>从 <code>src</code> 所指向的宽字符数组准确复制 <code>count</code> 个相继的宽字符到 <code>dest</code> 所指向的宽字符数组。若对象重叠，则行为未定义。若 <code>count</code> 为零，则函数不做任何事。</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>dest</td>
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<td>-</td>
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<td>指向复制目标宽字符数组的指针</td>
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</tr>
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<tr class="t-par">
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<td>src</td>
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<td>-</td>
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<td>指向复制来源宽字符数组的指针</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>要复制的宽字符数</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><code>dest</code></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>此函数对字节字符串的类似版本是 <span class="t-lc"><a href="cpp-string-byte-strncpy.html">std::strncpy</a></span> ，而非 <span class="t-lc"><a href="cpp-string-byte-strcpy.html">std::strcpy</a></span>。</p>
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<p>此函数不考虑本地环境，而且不关心其所复制的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> 对象的值：亦复制空字符还有非法字符。</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 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 <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="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">wchar_t</span> from1<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> L<span class="st0">"नमस्ते"</span><span class="sy4">;</span>
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<span class="kw4">const</span> size_t sz1 <span class="sy1">=</span> sizeof from1 <span class="sy2">/</span> sizeof <span class="sy2">*</span>from1<span class="sy4">;</span>
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<span class="kw4">wchar_t</span> from2<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> L<span class="st0">"Բարև"</span><span class="sy4">;</span>
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<span class="kw4">const</span> size_t sz2 <span class="sy1">=</span> sizeof from2 <span class="sy2">/</span> sizeof <span class="sy2">*</span>from2<span class="sy4">;</span>
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<span class="kw4">wchar_t</span> to<span class="br0">[</span>sz1 <span class="sy2">+</span> sz2<span class="br0">]</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">wmemcpy</span><span class="br0">(</span>to, from1, sz1<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 复制 from1 ，沿着其空终止符</span>
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std<span class="sy4">::</span><span class="me2">wmemcpy</span><span class="br0">(</span>to <span class="sy2">+</span> sz1, from2, sz2<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 后附 from2 ，沿着其空终止符</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="kw1757">std::<span class="me2">cout</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">"Wide array contains: "</span><span class="sy4">;</span>
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<span class="kw1">for</span><span class="br0">(</span>size_t n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1"><</span> sizeof to <span class="sy2">/</span> sizeof <span class="sy2">*</span>to<span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span>
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<span class="kw1">if</span><span class="br0">(</span>to<span class="br0">[</span>n<span class="br0">]</span><span class="br0">)</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> to<span class="br0">[</span>n<span class="br0">]</span><span class="sy4">;</span>
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<span class="kw1">else</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">"<span class="es1">\\</span>0"</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">'<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">Wide array contains: नमस्ते\0Բարև\0</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-strncpy.html"><span class="t-lines"><span>strncpy</span></span></a></div>
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</div>
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</td>
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<td>复制来自一个字符串的一定量字符给另一个<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-wmemmove.html"><span class="t-lines"><span>wmemmove</span></span></a></div>
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</div>
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</td>
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<td>在两个可能重叠的数组间复制一定量宽字符<br />
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<span class="t-mark">(函数)</span></td>
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</table>
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</div>
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<div class="visualClear"></div>
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