216 lines
11 KiB
HTML
216 lines
11 KiB
HTML
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<title>std::discard_block_engine</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_random_discard_block_engine skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>discard_block_engine</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-numeric.html">numeric</a>‎ | <a href="cpp-numeric-random.html">random</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-random.html"><random></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><br /></span>
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<p> <span class="kw1">class</span> Engine,<br />
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<a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> P, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> R<br /></p>
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<span class="sy1">></span> <span class="kw1">class</span> discard_block_engine<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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<p><code>discard_block_engine</code> 是伪随机数引擎适配器，它忽略基础引擎所产生的一定量数据。生成器只从基础引擎生成的每个 <code>P</code> 大小的块保留 <code>R</code> 个数，舍弃剩余的数。</p>
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<h3><span class="mw-headline" id=".E6.A8.A1.E6.9D.BF.E5.BD.A2.E5.8F.82">模板形参</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>Engine</td>
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<td>-</td>
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<td>包装的引擎类型</td>
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</tr>
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<tr class="t-par">
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<td>P</td>
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<td>-</td>
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<td>块大小。期待 <span class="mjax" style="display:none">\(\small{P>0}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">P > 0</span> 。</td>
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</tr>
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<tr class="t-par">
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<td>R</td>
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<td>-</td>
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<td>每块的使用数的数量。期待 <span class="mjax" style="display:none">\(\small{0<R\le P}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">0 < R ≤ P</span> 。</td>
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<tr class="t-par-hitem">
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<td colspan="3">类型要求</td>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>Engine</code> 必须满足<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> 的要求。</td>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
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<td>成员类型</td>
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<td>定义</td>
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<td><code>result_type</code><span class="t-mark-rev t-since-cxx11">(C++11)</span></td>
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<td><code>Engine::result_type</code></td>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-numeric-random-discard_block_engine-discard_block_engine.html"><span class="t-lines"><span>(构造函数)</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>构造引擎适配器<br />
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<span class="t-mark">(公开成员函数)</span></td>
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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-discard_block_engine-seed.html"><span class="t-lines"><span>seed</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>设置底层引擎的状态<br />
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<span class="t-mark">(公开成员函数)</span></td>
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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-discard_block_engine-base.html"><span class="t-lines"><span>base</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>返回底层引擎<br />
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<span class="t-mark">(公开成员函数)</span></td>
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<td colspan="2">
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<h5><span class="mw-headline" id=".E7.94.9F.E6.88.90">生成</span></h5>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-random-discard_block_engine-operator().html"><span class="t-lines"><span>operator()</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>令底层引擎的状态前进并返回生成的值<br />
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<span class="t-mark">(公开成员函数)</span></td>
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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-discard_block_engine-discard.html"><span class="t-lines"><span>discard</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>令适配器状态前进指定量<br />
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<span class="t-mark">(公开成员函数)</span></td>
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<td colspan="2">
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<h5><span class="mw-headline" id=".E7.89.B9.E5.BE.81">特征</span></h5>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-random-discard_block_engine-min.html"><span class="t-lines"><span>min</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</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>获取底层引擎输出范围中的最小可能值。<br />
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<span class="t-mark">(公开静态成员函数)</span></td>
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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-discard_block_engine-max.html"><span class="t-lines"><span>max</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</span> <span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</td>
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<td>获取底层引擎输出范围中最大的可能值。<br />
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<span class="t-mark">(公开静态成员函数)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-random-discard_block_engine-operator_cmp.html"><span class="t-lines"><span>operator==</span><span>operator!=</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><span class="t-mark-rev t-since-cxx11">(C++11)</span><span class="t-mark-rev t-until-cxx20">(C++20 中移除)</span></span></span></div>
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</div>
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</td>
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<td>比较适配器和底层引擎的内部状态<br />
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<span class="t-mark">(函数)</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-discard_block_engine-operator_ltltgtgt.html"><span class="t-lines"><span>operator<<</span><span>operator>></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>在伪随机数引擎适配器上进行流输入和输出<br />
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<span class="t-mark">(函数)</span></td>
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</table>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">成员常量</span></h3>
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<td>
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<div class="t-dsc-member-div">
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<div><span class="t-lines"><span><span class="t-dsc-small">constexpr size_t</span> block_size</span></span></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</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>块大小 <code>P</code><br />
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<span class="t-mark">(公开静态成员常量)</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><span class="t-lines"><span><span class="t-dsc-small">constexpr size_t</span> used_block</span></span></div>
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<div><span class="t-lines"><span><span class="t-cmark">[静态]</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>每块用的数字数 <code>R</code><br />
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<span class="t-mark">(公开静态成员常量)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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