141 lines
10 KiB
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141 lines
10 KiB
HTML
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<title>C++ 具名要求：均匀随机位生成器 (UniformRandomBitGenerator)</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_named_req_UniformRandomBitGenerator skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">C++ 具名要求：</span><span style="font-style:italic">均匀随机位生成器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UniformRandomBitGenerator)</span></h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-named_req.html">named req</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<p>均匀随机位生成器是返回无符号整数值的函数对象，可能结果范围中的每个值都（理想情况）拥有等概率。</p>
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<p>均匀随机位生成器不是有意用做随机数生成器的：它们被用作随机位的源（为效率大量生成）。任何均匀随机位生成器均可被插入任何<a href="cpp-numeric-random.html">随机数分布</a>，以获得随机数（正式而言是随机变量）。</p>
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<h3><span class="mw-headline" id=".E8.A6.81.E6.B1.82">要求</span></h3>
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<p>类型 <code>G</code> 满足<span style="font-style:italic">均匀随机位生成器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UniformRandomBitGenerator)</span> ，若</p>
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<p>给定</p>
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<ul>
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<li><code>T</code> ， <code>G::result_type</code> 所指名的类型</li>
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<li><code>g</code> ， <code>G</code> 类型的值</li>
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</ul>
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<p>下列表达式必须合法且拥有其指定的效应</p>
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<table class="wikitable">
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<tr>
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<th>表达式</th>
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<th>返回类型</th>
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<th>要求</th>
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</tr>
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<tr>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">G<span class="sy4">::</span><span class="me2">result_type</span></span></span></td>
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<td><code>T</code></td>
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<td><code>T</code> 是无符号整数类型</td>
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</tr>
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<tr>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">G<span class="sy4">::</span><span class="me2">min</span><span class="br0">(</span><span class="br0">)</span></span></span></td>
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<td><code>T</code></td>
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<td>返回 G 的 operator() 可返回的最小值。值严格小于 <code>G::max()</code> 。函数必须是 constexpr 。</td>
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</tr>
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<tr>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">G<span class="sy4">::</span><span class="me2">max</span><span class="br0">(</span><span class="br0">)</span></span></span></td>
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<td><code>T</code></td>
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<td>返回 G 的 operator() 可返回的最大值。值严格大于 <code>G::min()</code> 。函数必须是 constexpr 。</td>
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</tr>
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<tr>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">g<span class="br0">(</span><span class="br0">)</span></span></span></td>
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<td><code>T</code></td>
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<td>返回闭区间 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">[</span>G<span class="sy4">::</span><span class="me2">min</span><span class="br0">(</span><span class="br0">)</span>, G<span class="sy4">::</span><span class="me2">max</span><span class="br0">(</span><span class="br0">)</span><span class="br0">]</span></span></span> 中的值。拥有均摊常数复杂度。</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>所有<a href="cpp-named_req-RandomNumberEngine.html"><span style="font-style:italic">随机数引擎</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(RandomNumberEngine)</span></a> 均满足此要求。</p>
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<h3><span class="mw-headline" id=".E6.A0.87.E5.87.86.E5.BA.93">标准库</span></h3>
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<p>下列标准库设施期待<span style="font-style:italic">均匀随机位生成器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UniformRandomBitGenerator)</span> 类型。</p>
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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-algorithm-random_shuffle.html"><span class="t-lines"><span>random_shuffle</span><span>shuffle</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(C++17 前)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>随机重排范围中的元素<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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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-numeric-random-generate_canonical.html"><span class="t-lines"><span>generate_canonical</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>给定精度的均匀分布在 [0, 1) 上的实数值<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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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-numeric-random-uniform_int_distribution.html"><span class="t-lines"><span>uniform_int_distribution</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>产生在一个范围上均匀分布的整数值<br />
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<span class="t-mark">(类模板)</span></td>
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</tr>
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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-numeric-random-uniform_real_distribution.html"><span class="t-lines"><span>uniform_real_distribution</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>产生在一个范围上均匀分布的实数值<br />
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<span class="t-mark">(类模板)</span></td>
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</tr>
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<tr class="t-dsc">
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<td colspan="2">所有其他随机数分布</td>
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</tr>
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</table>
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<p>下列标准库设施满足<span style="font-style:italic">均匀随机位生成器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UniformRandomBitGenerator)</span> 而不另外满足<a href="cpp-named_req-RandomNumberEngine.html"><span style="font-style:italic">随机数引擎</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(RandomNumberEngine)</span></a> ：</p>
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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-numeric-random-random_device.html"><span class="t-lines"><span>random_device</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>使用硬件熵源的非确定随机数生成器<br />
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<span class="t-mark">(类)</span></td>
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</tr>
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</table>
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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"></table>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-random-uniform_random_bit_generator.html"><span class="t-lines"><span>uniform_random_bit_generator</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>指定类型具备作为均匀随机位生成器的资格<br />
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<span class="t-mark">(概念)</span></td>
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</tr>
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</table>
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<table>
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<tr>
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<td></td>
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</table>
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</div>
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<div class="visualClear"></div>
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