131 lines
10 KiB
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131 lines
10 KiB
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<title>std::wbuffer_convert<Codecvt,Elem,Tr>::wbuffer_convert</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::wbuffer_convert<Codecvt,Elem,Tr>::</span>wbuffer_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-wbuffer_convert.html">wbuffer 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">wbuffer_convert<span class="br0">(</span><span class="br0">)</span> <span class="sy4">:</span> wbuffer_convert<span class="br0">(</span>nullptr<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> wbuffer_convert<span class="br0">(</span> <a href="cpp-io-basic_streambuf.html"><span class="kw1724">std::<span class="me2">streambuf</span></span></a><span class="sy2">*</span> bytebuf,<br /></span>
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<p> Codecvt<span class="sy2">*</span> pcvt <span class="sy1">=</span> new Codecvt,<br /></p>
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state_type state <span class="sy1">=</span> state_type<span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<td class="t-dcl-nopad"></td>
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<tr class="t-dcl t-since-cxx14">
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<div><span class="mw-geshi cpp source-cpp">wbuffer_convert<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-locale-wbuffer_convert.html"><span class="kw1900">std::<span class="me2">wbuffer_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>(3)</td>
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<td><span class="t-mark-rev t-since-cxx14">(C++14 起)</span></td>
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<tr class="t-dcl-sep">
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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> 以指定的底层字节流、指定的 <code>codecvt</code> 平面和指定的初始转换状态构造 <code>wbuffer_convert</code> 对象（所有参数均为可选）。</div>
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<div class="t-li1"><span class="t-li">3)</span> 复制构造函数被删除。 <code>wbuffer_convert</code> 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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<table class="t-par-begin">
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<tr class="t-par">
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<td>bytebuf</td>
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<td>-</td>
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<td>指向作为底层窄字符流作用的 std::streambuf 的指针</td>
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</tr>
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<tr class="t-par">
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<td>pcvt</td>
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<td>-</td>
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<td>指向独立（不为 locale 所管理）的 <span class="t-lc"><a href="cpp-locale-codecvt.html">std::codecvt</a></span> 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>字符转换状态的初始值</td>
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</tr>
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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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<tr>
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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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</tr>
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<tr>
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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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</tr>
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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 <sstream></span>
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<span class="co2">#include <locale></span>
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<span class="co2">#include <codecvt></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">// 包装 UTF-8 字符串流于 UCS4 wbuffer_convert 中</span>
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<a href="cpp-io-basic_stringbuf.html"><span class="kw1726">std::<span class="me2">stringbuf</span></span></a> utf8buf<span class="br0">(</span>u8<span class="st0">"z<span class="es3">\u00df</span><span class="es3">\u6c34</span><span class="es4">\U0001f34c</span>"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 或 u8"zß水🍌"</span>
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<span class="co1">// 或 "\x7a\xc3\x9f\xe6\xb0\xb4\xf0\x9f\x8d\x8c";</span>
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<a href="cpp-locale-wbuffer_convert.html"><span class="kw1900">std::<span class="me2">wbuffer_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> conv_in<span class="br0">(</span><span class="sy3">&</span>utf8buf<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-basic_istream.html"><span class="kw1741">std::<span class="me2">wistream</span></span></a> ucsbuf<span class="br0">(</span><span class="sy3">&</span>conv_in<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">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Reading from a UTF-8 stringbuf via wbuffer_convert:<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">for</span><span class="br0">(</span><span class="kw4">wchar_t</span> c<span class="sy4">;</span> ucsbuf.<span class="me1">get</span><span class="br0">(</span>c<span class="br0">)</span><span class="sy4">;</span> <span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <a href="cpp-io-manip-hex.html"><span class="kw1782">std::<span class="me2">hex</span></span></a> <span class="sy1"><<</span> <a href="cpp-io-manip-showbase.html"><span class="kw1766">std::<span class="me2">showbase</span></span></a> <span class="sy1"><<</span> c <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="co1">// 包装具 UTF-8 的 std::cout 于 UCS4 wbuffer_convert 中以输出 UCS4</span>
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<a href="cpp-locale-wbuffer_convert.html"><span class="kw1900">std::<span class="me2">wbuffer_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> conv_out<span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-basic_ostream.html"><span class="kw1743">std::<span class="me2">wostream</span></span></a> out<span class="br0">(</span><span class="sy3">&</span>conv_out<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">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Sending UCS4 data to std::cout via wbuffer_convert:<span class="es1">\n</span>"</span><span class="sy4">;</span>
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out <span class="sy1"><<</span> L<span class="st0">"z<span class="es3">\u00df</span><span class="es3">\u6c34</span><span class="es4">\U0001f34c</span><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>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">Reading from a UTF-8 stringbuf via wbuffer_convert produces
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0x7a
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0xdf
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0x6c34
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0x1f34c
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Sending UCS4 data to std::cout via wbuffer_convert:
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zß水🍌</pre></div>
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