145 lines
12 KiB
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145 lines
12 KiB
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<title>operator<<,>>(std::bitset)</title>
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<h1 id="firstHeading" class="firstHeading">operator<<,>><small>(std::bitset)</small></h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a>‎ | <a href="cpp-utility-bitset.html">bitset</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-bitset.html"><bitset></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span><span class="kw1">class</span> CharT, <span class="kw1">class</span> Traits, size_t N<span class="sy1">></span><br /></span>
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<p><a href="cpp-io-basic_ostream.html"><span class="kw1715">std::<span class="me2">basic_ostream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span><span class="sy3">&</span> operator<span class="sy1"><<</span><span class="br0">(</span><a href="cpp-io-basic_ostream.html"><span class="kw1715">std::<span class="me2">basic_ostream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span><span class="sy3">&</span> os,<br /></p>
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<span class="kw4">const</span> <a href="cpp-utility-bitset.html"><span class="kw1027">std::<span class="me2">bitset</span></span></a><span class="sy1"><</span>N<span class="sy1">></span><span class="sy3">&</span> x<span class="br0">)</span><span class="sy4">;</span></div>
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<td>(1)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span><span class="kw1">class</span> CharT, <span class="kw1">class</span> Traits, size_t N<span class="sy1">></span><br /></span>
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<p><a href="cpp-io-basic_istream.html"><span class="kw1713">std::<span class="me2">basic_istream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span><span class="sy3">&</span> operator<span class="sy1">>></span><span class="br0">(</span><a href="cpp-io-basic_istream.html"><span class="kw1713">std::<span class="me2">basic_istream</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span><span class="sy3">&</span> is,<br /></p>
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<a href="cpp-utility-bitset.html"><span class="kw1027">std::<span class="me2">bitset</span></span></a><span class="sy1"><</span>N<span class="sy1">></span><span class="sy3">&</span> x<span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<p>从字符流插入或释出 bitset 。</p>
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<div class="t-li1"><span class="t-li">1)</span> 写 bitset <code>x</code> 入字符流 <code>os</code> ，如同首先用 <span class="t-lc"><a href="cpp-utility-bitset-to_string.html">to_string()</a></span> 将它转换成 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span></span></span> ，再用 <a href="cpp-string-basic_string-operator_ltltgtgt.html"><tt>operator<<</tt></a> （对字符串是<a href="cpp-named_req-FormattedOutputFunction.html"><span style="font-style:italic">有格式输出函数</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(FormattedOutputFunction)</span></a> ）将它写入 <code>os</code> 。为一与零使用的字符，通过以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">'1'</span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">'0'</span></span></span> 为参数调用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-locale-use_facet.html"><span class="kw1897">std::<span class="me2">use_facet</span></span></a><span class="sy1"><</span><a href="cpp-locale-ctype.html"><span class="kw1938">std::<span class="me2">ctype</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span><span class="br0">(</span>os.<span class="me1">getloc</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>.<span class="me1">widen</span><span class="br0">(</span><span class="br0">)</span></span></span> 从当前感染的本地环境获得。</div>
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<div class="t-li1"><span class="t-li">2)</span> 表现为<a href="cpp-named_req-FormattedInputFunction.html"><span style="font-style:italic">有格式输入函数</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(FormattedInputFunction)</span></a> 。构造并检查 sentry 对象，这可能跳过前导空白符，之后从 <code>is</code> 释出至多 <code>N</code> 个字符，并存储字符于 bitset <code>x</code> 。</div>
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<p>释出字符直至</p>
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<ul>
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<li>已读取 <code>N</code> 个字符</li>
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<li>文件尾发生于 <code>is</code> ，或</li>
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<li>下个字符既非 <span class="t-c"><span class="mw-geshi cpp source-cpp">is.<span class="me1">widen</span><span class="br0">(</span><span class="st0">'0'</span><span class="br0">)</span></span></span> 亦非 <span class="t-c"><span class="mw-geshi cpp source-cpp">is.<span class="me1">widen</span><span class="br0">(</span><span class="st0">'1'</span><span class="br0">)</span></span></span> 。</li>
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</ul>
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<p>若 <code>N > 0</code> 且未释出字符，则调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">is.<span class="me1">setstate</span><span class="br0">(</span>ios_base<span class="sy4">::</span><span class="me2">failbit</span><span class="br0">)</span></span></span> 。</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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<td>os</td>
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<td>-</td>
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<td>要写入的字符流</td>
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<tr class="t-par">
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<td>is</td>
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<td>-</td>
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<td>要读取的字符流</td>
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<td>x</td>
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<td>-</td>
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<td>要读取或写入的 bitset</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>操作于上的字符流，例如 <code>os</code> 或 <code>is</code> 。</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="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <bitset></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <sstream></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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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> bit_string <span class="sy1">=</span> <span class="st0">"001101"</span><span class="sy4">;</span>
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<a href="cpp-io-basic_istringstream.html"><span class="kw1735">std::<span class="me2">istringstream</span></span></a> bit_stream<span class="br0">(</span>bit_string<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-utility-bitset.html"><span class="kw1027">std::<span class="me2">bitset</span></span></a><span class="sy1"><</span><span class="nu0">3</span><span class="sy1">></span> b1<span class="sy4">;</span>
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bit_stream <span class="sy1">>></span> b1<span class="sy4">;</span> <span class="co1">// 读取 "001" ，流仍保有 "101"</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> b1 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<a href="cpp-utility-bitset.html"><span class="kw1027">std::<span class="me2">bitset</span></span></a><span class="sy1"><</span><span class="nu0">8</span><span class="sy1">></span> b2<span class="sy4">;</span>
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bit_stream <span class="sy1">>></span> b2<span class="sy4">;</span> <span class="co1">// 读取 "101" ，产出 8 位集为 "00000101"</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> b2 <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>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">001
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00000101</pre></div>
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</div>
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</div>
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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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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3199">LWG 3199</a></td>
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<td>C++98</td>
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<td>释出 <code>std::bitset<0></code> 始终设置 <code>failbit</code></td>
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<td>这种释出始终不设置 <code>failbit</code></td>
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</tr>
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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-utility-bitset-operator_ltltgtgt.html"><span class="t-lines"><span>operator<<=</span><span>operator>>=</span><span>operator<<</span><span>operator>></span></span></a></div>
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</div>
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</td>
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<td>进行二进制左移和右移<br />
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<span class="t-mark">(公开成员函数)</span></td>
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<div class="visualClear"></div>
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