145 lines
10 KiB
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145 lines
10 KiB
HTML
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<title>std::wstring_convert<Codecvt,Elem,Wide_alloc,Byte_alloc>::wstring_convert</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::wstring_convert<Codecvt,Elem,Wide_alloc,Byte_alloc>::</span>wstring_convert</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-wstring_convert.html">wstring convert</a></span></div>
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<table class="t-dcl-begin">
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<div><span class="mw-geshi cpp source-cpp">wstring_convert<span class="br0">(</span><span class="br0">)</span> <span class="sy4">:</span> wstring_convert<span class="br0">(</span> new Codecvt <span class="br0">)</span> <span class="br0">{</span> <span class="br0">}</span></span></div>
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<td>(1)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> wstring_convert<span class="br0">(</span> Codecvt<span class="sy2">*</span> pcvt <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
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<div><span class="mw-geshi cpp source-cpp">wstring_convert<span class="br0">(</span> Codecvt<span class="sy2">*</span> pcvt, state_type state<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(3)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> wstring_convert<span class="br0">(</span> <span class="kw4">const</span> byte_string<span class="sy3">&</span> byte_err,<br />
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<span class="kw4">const</span> wide_string<span class="sy3">&</span> wide_err <span class="sy1">=</span> wide_string<span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(4)</td>
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<div><span class="mw-geshi cpp source-cpp">wstring_convert<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-locale-wstring_convert.html"><span class="kw1899">std::<span class="me2">wstring_convert</span></span></a><span class="sy3">&</span><span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></div>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 起)</span></td>
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<td></td>
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<td></td>
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<td></td>
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<div class="t-li1"><span class="t-li">1)</span> 默认构造函数。</div>
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<div class="t-li1"><span class="t-li">2)</span> 以指定的转换平面，用初始迁移状态和错误字符串的默认构造值构造 <code>wstring_convert</code> 对象。</div>
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<div class="t-li1"><span class="t-li">3)</span> 以指定的转换平面和指定的初始迁移状态，用默认构造的错误字符串值构造 <code>wstring_convert</code> 对象。</div>
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<div class="t-li1"><span class="t-li">4)</span> 以指定的错误字符串，以 <span class="t-c"><span class="mw-geshi cpp source-cpp">new Codecvt</span></span> 为转换平面并以 <code>state_type</code> 的默认构造值为初始状态构造 <code>wstring_convert</code> 对象。</div>
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<div class="t-li1"><span class="t-li">5)</span> 复制构造函数被删除， wstring_convert 非<a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 。</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<td>pcvt</td>
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<td>-</td>
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<td>指向 <code>Codecvt</code> 类型转换平面的指针（若此指针为空则行为未定义）</td>
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</tr>
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<tr class="t-par">
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<td>state</td>
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<td>-</td>
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<td>转换迁移状态的初始值</td>
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<td>byte_err</td>
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<td>-</td>
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<td>错误时显示的窄字符串</td>
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<tr class="t-par">
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<td>wide_err</td>
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<td>-</td>
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<td>错误时显示的宽字符串</td>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
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<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
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<table class="dsctable" style="font-size:0.8em">
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<th>DR</th>
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<th>应用于</th>
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<th>出版时的行为</th>
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<th>正确行为</th>
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<td><a rel="nofollow" class="external text" href="https://wg21.link/P0935R0">P0935R0</a></td>
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<td>C++11</td>
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<td>默认构造函数曾为 explicit</td>
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<td>使之为隐式</td>
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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 <locale></span>
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<span class="co2">#include <utility></span>
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<span class="co2">#include <codecvt></span>
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<span class="co1">// 为 wstring/wbuffer convert 适配绑定本地环境的平面的工具包装器</span>
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<span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> Facet<span class="sy1">></span>
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<span class="kw1">struct</span> deletable_facet <span class="sy4">:</span> Facet
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<span class="br0">{</span>
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<span class="kw1">using</span> Facet<span class="sy4">::</span><span class="me2">Facet</span><span class="sy4">;</span> <span class="co1">// 继承构造函数</span>
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~deletable_facet<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span><span class="br0">}</span>
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<span class="br0">}</span><span class="sy4">;</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">// UTF-16le / UCS4 转换</span>
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<a href="cpp-locale-wstring_convert.html"><span class="kw1899">std::<span class="me2">wstring_convert</span></span></a><span class="sy1"><</span>
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<a href="cpp-locale-codecvt_utf16.html"><span class="kw1984">std::<span class="me2">codecvt_utf16</span></span></a><span class="sy1"><</span><span class="kw4">char32_t</span>, <span class="nu12">0x10ffff</span>, <a href="cpp-locale-codecvt_mode.html"><span class="kw1989">std::<span class="me2">little_endian</span></span></a><span class="sy1">></span>
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<span class="sy1">></span> u16to32<span class="sy4">;</span>
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<span class="co1">// UTF-8 / 宽字符串转换，带定制消息</span>
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<a href="cpp-locale-wstring_convert.html"><span class="kw1899">std::<span class="me2">wstring_convert</span></span></a><span class="sy1"><</span><a href="cpp-locale-codecvt_utf8.html"><span class="kw1983">std::<span class="me2">codecvt_utf8</span></span></a><span class="sy1"><</span><span class="kw4">wchar_t</span><span class="sy1">>></span> u8towide<span class="br0">(</span><span class="st0">"Error!"</span>, L<span class="st0">"Error!"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// GB18030 / 宽字符串转换平面</span>
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<span class="kw1">typedef</span> deletable_facet<span class="sy1"><</span><a href="cpp-locale-codecvt_byname.html"><span class="kw1976">std::<span class="me2">codecvt_byname</span></span></a><span class="sy1"><</span><span class="kw4">wchar_t</span>, <span class="kw4">char</span>, <a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1179">std::<span class="me2">mbstate_t</span></span></a><span class="sy1">>></span> F<span class="sy4">;</span>
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<a href="cpp-locale-wstring_convert.html"><span class="kw1899">std::<span class="me2">wstring_convert</span></span></a><span class="sy1"><</span>F<span class="sy1">></span> gbtowide<span class="br0">(</span>new F<span class="br0">(</span><span class="st0">"zh_CN.gb18030"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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