108 lines
8.4 KiB
HTML
108 lines
8.4 KiB
HTML
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<title>std::mbsinit</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_multibyte_mbsinit 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>mbsinit</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-multibyte.html">multibyte</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">int</span> mbsinit<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1178">std::<span class="me2">mbstate_t</span></span></a><span class="sy2">*</span> ps<span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>若 <code>ps</code> 不是空指针，则 <code>mbsinit</code> 函数确定被指向的 <span class="t-lc"><a href="cpp-string-multibyte-mbstate_t.html">std::mbstate_t</a></span> 对象是否描述初始迁移状态。</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>尽管零初始化的 <span class="t-lc"><a href="cpp-string-multibyte-mbstate_t.html">std::mbstate_t</a></span> 始终表示初始转换状态，亦可能有其他 <span class="t-lc"><a href="cpp-string-multibyte-mbstate_t.html">std::mbstate_t</a></span> 值表示初始转换状态。</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>ps</td>
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<td>-</td>
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<td>指向要检验的 std::mbstate_t 对象的指针</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 <code>ps</code> 不是空指针且不表示初始迁移状态则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> ，否则为非零值。</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 <clocale></span>
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<span class="co2">#include <string></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <cwchar></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="co1">// 允许 mbrlen() 以 UTF-8 多字节编码工作</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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<span class="co1">// UTF-8 窄多字节编码</span>
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<a href="cpp-string-basic_string.html"><span class="kw1229">std::<span class="me2">string</span></span></a> str <span class="sy1">=</span> u8<span class="st0">"水"</span><span class="sy4">;</span> <span class="co1">// 或 u8"\u6c34" 或 "\xe6\xb0\xb4"</span>
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<a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1178">std::<span class="me2">mbstate_t</span></span></a> mb <span class="sy1">=</span> <a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1178">std::<span class="me2">mbstate_t</span></span></a><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span><a href="cpp-string-multibyte-mbrlen.html"><span class="kw1169">std::<span class="me2">mbrlen</span></span></a><span class="br0">(</span><span class="sy3">&</span>str<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span>, <span class="nu0">1</span>, <span class="sy3">&</span>mb<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="sy3">!</span>std<span class="sy4">::</span><span class="me2">mbsinit</span><span class="br0">(</span><span class="sy3">&</span>mb<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"After processing the first 1 byte of "</span> <span class="sy1"><<</span> str
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<span class="sy1"><<</span> <span class="st0">" the conversion state is not initial<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><span class="kw4">void</span><span class="br0">)</span><a href="cpp-string-multibyte-mbrlen.html"><span class="kw1169">std::<span class="me2">mbrlen</span></span></a><span class="br0">(</span><span class="sy3">&</span>str<span class="br0">[</span><span class="nu0">1</span><span class="br0">]</span>, str.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="nu0">1</span>, <span class="sy3">&</span>mb<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span>std<span class="sy4">::</span><span class="me2">mbsinit</span><span class="br0">(</span><span class="sy3">&</span>mb<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"After processing the remaining 2 bytes of "</span> <span class="sy1"><<</span> str
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<span class="sy1"><<</span> <span class="st0">", the conversion state is initial conversion state<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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<p>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">After processing the first 1 byte of 水 the conversion state is not initial
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After processing the remaining 2 bytes of 水, the conversion state is initial conversion state</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-string-multibyte-mbstate_t.html"><span class="t-lines"><span>mbstate_t</span></span></a></div>
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</div>
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</td>
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<td>迭代多字节字符串所需的转换状态信息<br />
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<span class="t-mark">(类)</span></td>
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