239 lines
22 KiB
HTML
239 lines
22 KiB
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<title>std::bitset<N>::bitset</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::bitset<N>::</span>bitset</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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<td rowspan="142">(1)</td>
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<div><span class="mw-geshi cpp source-cpp">bitset<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> bitset<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<td rowspan="142">(2)</td>
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<div><span class="mw-geshi cpp source-cpp">bitset<span class="br0">(</span> <span class="kw4">unsigned</span> <span class="kw4">long</span> val <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> bitset<span class="br0">(</span> <span class="kw4">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span> val <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<td rowspan="142">(3)</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, <span class="kw1">class</span> Alloc <span class="sy1">></span><br /></span>
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<p><span class="kw1">explicit</span> bitset<span class="br0">(</span> <span class="kw4">const</span> <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,Alloc<span class="sy1">></span><span class="sy3">&</span> str,<br />
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<span class="kw1">typename</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">size_type</span><br />
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pos <span class="sy1">=</span> <span class="nu0">0</span>,<br />
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<span class="kw1">typename</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">size_type</span><br /></p>
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n <span class="sy1">=</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">npos</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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<tr class="t-dcl t-since-cxx11">
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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, <span class="kw1">class</span> Alloc <span class="sy1">></span><br /></span>
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<p><span class="kw1">explicit</span> bitset<span class="br0">(</span> <span class="kw4">const</span> <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,Alloc<span class="sy1">></span><span class="sy3">&</span> str,<br />
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<span class="kw1">typename</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">size_type</span><br />
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pos <span class="sy1">=</span> <span class="nu0">0</span>,<br />
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<span class="kw1">typename</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">size_type</span><br />
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n <span class="sy1">=</span> <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,Alloc<span class="sy1">></span><span class="sy4">::</span><span class="me2">npos</span>,<br />
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CharT zero <span class="sy1">=</span> CharT<span class="br0">(</span><span class="st0">'0'</span><span class="br0">)</span>,<br /></p>
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CharT one <span class="sy1">=</span> CharT<span class="br0">(</span><span class="st0">'1'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></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="sy1">></span><br /></span>
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<p><span class="kw1">explicit</span> bitset<span class="br0">(</span> <span class="kw4">const</span> CharT<span class="sy2">*</span> str,<br />
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<span class="kw1">typename</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span><span class="sy4">::</span><span class="me2">size_type</span><br />
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n <span class="sy1">=</span> <a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">basic_string</span></span></a><span class="sy1"><</span>CharT<span class="sy1">></span><span class="sy4">::</span><span class="me2">npos</span>,<br />
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CharT zero <span class="sy1">=</span> CharT<span class="br0">(</span><span class="st0">'0'</span><span class="br0">)</span>,<br /></p>
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CharT one <span class="sy1">=</span> CharT<span class="br0">(</span><span class="st0">'1'</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<p>从数个数据源之一构造新的 bitset ：</p>
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<div class="t-li1"><span class="t-li">1)</span> 默认构造函数。构造所有位设为零的 bitset 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 构造 bitset ，初始化其首（最右、最低） <code>M</code> 位位置为对应 <code>val</code> 的位值，其中 <code>M</code> 是 <code>unsigned long long</code> 的位数和正在构造的 bitset 中的位数 <code>N</code> 的较小者。若 M 小于 N （ bitset 长于 <span class="t-rev-inl t-until-cxx11"><span>32</span> <span><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></span></span><span class="t-rev-inl t-since-cxx11"><span>64</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span> 位，对于典型的 unsigned <span class="t-rev-inl t-since-cxx11"><span>long</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span>long 实现），则剩余位位置被初始化为零。</div>
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<div class="t-li1"><span class="t-li">3)</span> 用 <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> <code>str</code> 中的字符构造 bitset 。能提供可选的起始位置 <code>pos</code> 和长度 <code>n</code> ，以及指代设置（ <code>one</code> ）和不设置（ <code>zero</code> ）位的替代值的字符。用 <code>Traits::eq()</code> 比较字符值。</div>
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<div class="t-li1"><span class="t-li"></span> 初始化字符串的有效长度是 min(<code>n</code>, <code>str.size() - pos</code>) 。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <code>pos > str.size()</code> ，则构造函数抛出 <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span> 。若 <code>str</code> 中检验到的任何字符非 <code>zero</code> 或 <code>one</code> ，则抛出 <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span> 。</div>
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<div class="t-li1"><span class="t-li">4)</span> 同 (3) ，但用 <code>CharT*</code> 代替 <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> 。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">bitset<span class="br0">(</span>n <span class="sy1">==</span> basic_string<span class="sy1"><</span>CharT<span class="sy1">></span><span class="sy4">::</span><span class="me2">npos</span> <span class="sy4">?</span> basic_string<span class="sy1"><</span>CharT<span class="sy1">></span><span class="br0">(</span>str<span class="br0">)</span> <span class="sy4">:</span> basic_string<span class="sy1"><</span>CharT<span class="sy1">></span><span class="br0">(</span>str, n<span class="br0">)</span>, <span class="nu0">0</span>, n, zero, one<span class="br0">)</span></span></span> 。</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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<td>val</td>
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<td>-</td>
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<td>用于初始化 bitset 的数字</td>
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</tr>
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<tr class="t-par">
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<td>str</td>
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<td>-</td>
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<td>用于初始化 bitset 的字符串</td>
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</tr>
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<tr class="t-par">
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<td>pos</td>
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<td>-</td>
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<td><code>str</code> 中的起始偏移</td>
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</tr>
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<tr class="t-par">
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<td>n</td>
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<td>-</td>
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<td>使用来自 <code>str</code> 的字符数</td>
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</tr>
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<tr class="t-par">
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<td>one</td>
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<td>-</td>
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<td>设置位于 <code>str</code> 中的替用字符</td>
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</tr>
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<tr class="t-par">
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<td>zero</td>
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<td>-</td>
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<td>不设置位于 <code>str</code> 中的替用字符</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<div class="t-li1"><span class="t-li">3)</span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp">pos <span class="sy1">></span> str.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span></span></span> 则为 <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span> ，若任何字符非一或零则为 <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span></div>
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<div class="t-li1"><span class="t-li">4)</span> <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span> ，若任何字符非一或零</div>
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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 <bitset></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 <climits></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">// 空构造函数</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> b1<span class="sy4">;</span> <span class="co1">// [0,0,0,0,0,0,0,0]</span>
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<span class="co1">// unsigned long long 构造函数</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="br0">(</span><span class="nu0">42</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,1,0,1,0,1,0]</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">70</span><span class="sy1">></span> bl<span class="br0">(</span><a href="cpp-types-climits.html"><span class="kw405">ULLONG_MAX</span></a><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,0,0,0,0,1,1,1,...,1,1,1] in C++11</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> bs<span class="br0">(</span><span class="nu12">0xfff0</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [1,1,1,1,0,0,0,0]</span>
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<span class="co1">// string 构造函数</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">"110010"</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> b3<span class="br0">(</span>bit_string<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,1,1,0,0,1,0]</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> b4<span class="br0">(</span>bit_string, <span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,0,0,0,0,1,0]</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> b5<span class="br0">(</span>bit_string, <span class="nu0">2</span>, <span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,0,0,0,0,0,1]</span>
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<span class="co1">// 使用自定义零/一数字的 string 构造函数</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> alpha_bit_string <span class="sy1">=</span> <span class="st0">"aBaaBBaB"</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> b6<span class="br0">(</span>alpha_bit_string, <span class="nu0">0</span>, alpha_bit_string.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span>,
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<span class="st0">'a'</span>, <span class="st0">'B'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,1,0,0,1,1,0,1]</span>
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<span class="co1">// 使用自定义数字的 char* 构造函数</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> b7<span class="br0">(</span><span class="st0">"XXXXYYYY"</span>, <span class="nu0">8</span>, <span class="st0">'X'</span>, <span class="st0">'Y'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// [0,0,0,0,1,1,1,1]</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="sy1"><<</span> b2 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span> <span class="sy1"><<</span> bl <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span> <span class="sy1"><<</span> bs <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> b3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span> <span class="sy1"><<</span> b4 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span> <span class="sy1"><<</span> b5 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span> <span class="sy1"><<</span> b6 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> b7 <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">
|
|
<pre class="de1">00000000
|
|
00101010
|
|
0000001111111111111111111111111111111111111111111111111111111111111111
|
|
11110000
|
|
00110010
|
|
00000010
|
|
00000001
|
|
01001101
|
|
00001111</pre></div>
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</div>
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</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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<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-utility-bitset-set.html"><span class="t-lines"><span>set</span></span></a></div>
|
|
</div>
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</td>
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|
<td>将位置为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 或者提供的值<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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|
<tr class="t-dsc">
|
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<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-utility-bitset-reset.html"><span class="t-lines"><span>reset</span></span></a></div>
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</div>
|
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</td>
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|
<td>将位置为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span><br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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