259 lines
15 KiB
HTML
259 lines
15 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<title>std::subtract_with_carry_engine</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_random_subtract_with_carry_engine skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>subtract_with_carry_engine</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-numeric.html">numeric</a>‎ | <a href="cpp-numeric-random.html">random</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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<table class="t-dcl-begin">
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<tbody>
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<td>
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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>
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<td></td>
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<td></td>
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<tr class="t-dcl t-since-cxx11">
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<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> UIntType,<br />
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<a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> w, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> s, <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> subtract_with_carry_engine<span class="sy4">;</span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<p><code>subtract_with_carry_engine</code> 是使用<a href="https://en.wikipedia.org/wiki/subtract_with_carry" class="extiw" title="enwiki:subtract with carry">带进位减法</a>算法的随机数引擎。</p>
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<p><code>subtract_with_carry_engine</code> 的状态由序列 <span class="mjax" style="display:none">\(\small{\{ X_i\}(0 \le i <r)}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">{X<span class="t-su t-su-b"><br />
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i</span>} (0 ≤ i <r)</span> 组成，每个 <span class="mjax" style="display:none">\(\small{X_i}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">X<span class="t-su t-su-b"><br />
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i</span></span> 均在区间 <span class="mjax" style="display:none">\(\small{[0, 2^w)}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">[0, 2<span class="t-su">w<br /></span>)</span> 中。</p>
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<p>令所有应用到序列的下标都对 <code>r</code> 取余， <code>c</code> 为进位值 0 或 1 。状态迁移按下列方式进行：</p>
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<ul>
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<li>令 <span class="mjax" style="display:none">\(\small{Y=X_{i-s}-X_{i-r}-c}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">Y=X<span class="t-su t-su-b"><br />
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i-s</span>-X<span class="t-su t-su-b"><br />
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i-r</span>-c</span><span class="texhtml" style="white-space: nowrap;"></span> ，</li>
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<li>设置 <span class="mjax" style="display:none">\(\small{X_i}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">X<span class="t-su t-su-b"><br />
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i</span></span> 为 <span class="mjax" style="display:none">\(\small{Y \mod 2^w}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">Y mod 2<span class="t-su">w<br /></span></span> ，若 <span class="mjax" style="display:none">\(\small{Y<0}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">Y<0</span> 则设置 <code>c</code> 为 1 ，否则设置为 0 。</li>
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</ul>
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<p>下列 typedef 定义拥有二个常用参数集的随机数引擎：</p>
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<table class="t-dsc-begin">
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<tr class="t-dsc-header">
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<td colspan="2">
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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>
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</tr>
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<tr class="t-dsc-hitem">
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<td>类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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<td><code>ranlux24_base</code><span class="t-mark-rev t-since-cxx11">(C++11)</span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">subtract_with_carry_engine</span><span class="sy1"><</span><a href="cpp-types-integer.html"><span class="kw126">std::<span class="me2">uint_fast32_t</span></span></a>, <span class="nu0">24</span>, <span class="nu0">10</span>, <span class="nu0">24</span><span class="sy1">></span></span></span></td>
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</tr>
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<tr class="t-dsc">
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<td><code>ranlux48_base</code><span class="t-mark-rev t-since-cxx11">(C++11)</span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">subtract_with_carry_engine</span><span class="sy1"><</span><a href="cpp-types-integer.html"><span class="kw127">std::<span class="me2">uint_fast64_t</span></span></a>, <span class="nu0">48</span>, <span class="nu0">5</span>, <span class="nu0">12</span><span class="sy1">></span></span></span></td>
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</tr>
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</table>
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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>UIntType</td>
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<td>-</td>
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<td>生成器所生成的结果类型。若它不是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">short</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">int</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span></span></span> 之一则效果未定义。</td>
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</tr>
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<tr class="t-par">
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<td>w</td>
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<td>-</td>
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<td>状态序列按位计的字大小， 0 < w <= <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-numeric_limits.html"><span class="kw344">std::<span class="me2">numeric_limits</span></span></a><span class="sy1"><</span>UIntType<span class="sy1">></span><span class="sy4">::</span><span class="me2">digits</span></span></span></td>
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</tr>
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<tr class="t-par">
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<td>s</td>
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<td>-</td>
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<td><i>短延迟</i></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><i>长延迟</i>，其中 0 < s < r</td>
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</tr>
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</table>
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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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<table class="t-dsc-begin">
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<tr class="t-dsc-hitem">
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<td>成员类型</td>
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<td>定义</td>
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</tr>
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<tr class="t-dsc">
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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>引擎生成的整数类型。若此非无符号整数类型则结果未定义。</td>
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</tr>
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</table>
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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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<table class="t-dsc-begin">
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<tr>
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<td colspan="2">
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<h5><span class="mw-headline" id=".E6.9E.84.E9.80.A0.E4.B8.8E.E6.92.AD.E7.A7.8D">构造与播种</span></h5>
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</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 t-dsc-member-nobold-div">
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<div><a href="cpp-numeric-random-subtract_with_carry_engine-subtract_with_carry_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<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>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-random-subtract_with_carry_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>设置引擎的当前状态<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>
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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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</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-subtract_with_carry_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>推进引擎状态并返回生成的值<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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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-subtract_with_carry_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>令引擎状态前进指定量<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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<tr>
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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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</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-subtract_with_carry_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></span></div>
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</div>
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</td>
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<td>获取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>
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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-subtract_with_carry_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></span></div>
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</div>
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</td>
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<td>获取输出范围中的最大可能值<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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<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-subtract_with_carry_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>比较两个伪随机数引擎的内部状态<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-subtract_with_carry_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>执行伪随机数引擎的流输入和输出<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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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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<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><span class="t-lines"><span><span class="t-dsc-small">constexpr size_t</span> word_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>模板形参 <code>w</code> ，字大小<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> short_lag</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>模板形参 <code>s</code> ，短延迟<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> long_lag</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>模板形参 <code>r</code> ，长延迟<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 UIntType</span> default_seed</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>常数值 <span class="t-c"><span class="mw-geshi cpp source-cpp">19780503u</span></span><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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</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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