250 lines
18 KiB
HTML
250 lines
18 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::div, std::ldiv, std::lldiv</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_math_div skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>div, <span style="font-size:0.7em; line-height:130%">std::</span>ldiv, <span style="font-size:0.7em; line-height:130%">std::</span>lldiv</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-math.html">math</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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<td>
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<div>定义于头文件 <code><a href="cpp-header-cstdlib.html"><cstdlib></a></code></div>
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</td>
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<td></td>
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<td></td>
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<td>
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">div_t</span> div<span class="br0">(</span> <span class="kw4">int</span> x, <span class="kw4">int</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td class="t-dcl-nopad"></td>
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<td>
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">ldiv_t</span> div<span class="br0">(</span> <span class="kw4">long</span> x, <span class="kw4">long</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td class="t-dcl-nopad"></td>
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">lldiv_t</span> div<span class="br0">(</span> <span class="kw4">long</span> <span class="kw4">long</span> x, <span class="kw4">long</span> <span class="kw4">long</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl">
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">ldiv_t</span> ldiv<span class="br0">(</span> <span class="kw4">long</span> x, <span class="kw4">long</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(4)</td>
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<td class="t-dcl-nopad"></td>
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">lldiv_t</span> lldiv<span class="br0">(</span> <span class="kw4">long</span> <span class="kw4">long</span> x, <span class="kw4">long</span> <span class="kw4">long</span> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-cinttypes.html"><cinttypes></a></code></div>
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<td></td>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">imaxdiv_t</span> div<span class="br0">(</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> x, <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(6)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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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">std<span class="sy4">::</span><span class="me2">imaxdiv_t</span> imaxdiv<span class="br0">(</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> x, <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> y <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(7)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>计算分子 <code>x</code> 除以分母 <code>y</code> 的商和余数。</p>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx11">
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<td>
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<p><code><cinttypes></code> 中提供 <code>std::div</code> 对 <code>std::intmax_t</code> 的重载,当且仅当 <code>std::intmax_t</code> 为扩展整数类型。</p>
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</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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</table>
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<table class="t-rev-begin">
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<tr class="t-rev t-until-cxx11">
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<td>
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<p>商是舍弃任何小数部分(向零截断)的代数商。余数满足 <span class="t-c"><span class="mw-geshi cpp source-cpp">quot <span class="sy2">*</span> y <span class="sy2">+</span> rem <span class="sy1">==</span> x</span></span> 。</p>
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</td>
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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-rev t-since-cxx11">
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<td>
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<p>商是表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的结果。余数是表达式 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">%</span>y</span></span> 的结果。</p>
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</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</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.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>x, y</td>
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<td>-</td>
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<td>整数值</td>
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</tr>
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</table>
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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>若余数与上皆能表示成对应类型(分别为 int 、 long 、 long long 、 std::imaxdiv_t )的对象,则返回作为定义于下的 <code>std::div_t</code> 、 <code>std::ldiv_t</code> 、 <code>std::lldiv_t</code> 、 <code>std::imaxdiv_t</code> 类型对象的二者:</p>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::div_t"><span style="font-size:0.7em; line-height:130%">std::</span>div_t</span></h2>
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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="kw1">struct</span> div_t <span class="br0">{</span> <span class="kw4">int</span> quot<span class="sy4">;</span> <span class="kw4">int</span> rem<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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<p>或</p>
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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="kw1">struct</span> div_t <span class="br0">{</span> <span class="kw4">int</span> rem<span class="sy4">;</span> <span class="kw4">int</span> quot<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</div>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::ldiv_t"><span style="font-size:0.7em; line-height:130%">std::</span>ldiv_t</span></h2>
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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="kw1">struct</span> ldiv_t <span class="br0">{</span> <span class="kw4">long</span> quot<span class="sy4">;</span> <span class="kw4">long</span> rem<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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<p>或</p>
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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="kw1">struct</span> ldiv_t <span class="br0">{</span> <span class="kw4">long</span> rem<span class="sy4">;</span> <span class="kw4">long</span> quot<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</div>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::lldiv_t"><span style="font-size:0.7em; line-height:130%">std::</span>lldiv_t</span></h2>
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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="kw1">struct</span> lldiv_t <span class="br0">{</span> <span class="kw4">long</span> <span class="kw4">long</span> quot<span class="sy4">;</span> <span class="kw4">long</span> <span class="kw4">long</span> rem<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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<p>或</p>
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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="kw1">struct</span> lldiv_t <span class="br0">{</span> <span class="kw4">long</span> <span class="kw4">long</span> rem<span class="sy4">;</span> <span class="kw4">long</span> <span class="kw4">long</span> quot<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</div>
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<div class="t-member">
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<h2><span class="mw-headline" id="std::imaxdiv_t"><span style="font-size:0.7em; line-height:130%">std::</span>imaxdiv_t</span></h2>
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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="kw1">struct</span> imaxdiv_t <span class="br0">{</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> quot<span class="sy4">;</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> rem<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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<p>或</p>
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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="kw1">struct</span> imaxdiv_t <span class="br0">{</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> rem<span class="sy4">;</span> <a href="cpp-types-integer.html"><span class="kw118">std::<span class="me2">intmax_t</span></span></a> quot<span class="sy4">;</span> <span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</div>
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<p>若余数或商之一无法表示,则行为未定义。</p>
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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>C++11 前,若运算数之一为负,则<a href="cpp-language-operator_arithmetic.html">内建除法与取余运算符</a>中商的舍入方向和余数的符号是实现定义的,但在 <code>std::div</code> 中已为良定义。</p>
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<p>多数平台上,单条 CPU 指令一同获得商与余数,而此函数可以活用这点,尽管编译器通常能够在适合处合并邻近的 / 与 % 。</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="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 <string></span>
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<span class="co2">#include <cmath></span>
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<span class="co2">#include <cstdlib></span>
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<span class="co2">#include <iostream></span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> itoa<span class="br0">(</span><span class="kw4">int</span> n, <span class="kw4">int</span> base<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> buf<span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">div_t</span> dv<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span> dv.<span class="me1">quot</span> <span class="sy1">=</span> n<span class="sy4">;</span>
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<span class="kw1">do</span> <span class="br0">{</span>
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dv <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">div</span><span class="br0">(</span>dv.<span class="me1">quot</span>, base<span class="br0">)</span><span class="sy4">;</span>
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buf <span class="sy2">+</span><span class="sy1">=</span> <span class="st0">"0123456789abcdef"</span><span class="br0">[</span>std<span class="sy4">::</span><span class="me2">abs</span><span class="br0">(</span>dv.<span class="me1">rem</span><span class="br0">)</span><span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 字符串字面量是数组</span>
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<span class="br0">}</span> <span class="kw1">while</span><span class="br0">(</span>dv.<span class="me1">quot</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>n<span class="sy1"><</span><span class="nu0">0</span><span class="br0">)</span> buf <span class="sy2">+</span><span class="sy1">=</span> <span class="st0">'-'</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="br0">{</span>buf.<span class="me1">rbegin</span><span class="br0">(</span><span class="br0">)</span>, buf.<span class="me1">rend</span><span class="br0">(</span><span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="br0">}</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-io-cout.html"><span class="kw1750">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> itoa<span class="br0">(</span><span class="nu0">12345</span>, <span class="nu0">10</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> itoa<span class="br0">(</span><span class="sy2">-</span><span class="nu0">12345</span>, <span class="nu0">10</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> itoa<span class="br0">(</span><span class="nu0">65535</span>, <span class="nu0">16</span><span class="br0">)</span> <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">12345
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-12345
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ffff</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-numeric-math-fmod.html"><span class="t-lines"><span>fmod</span><span>fmodf</span><span>fmodl</span></span></a></div>
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<div><span class="t-lines"><span></span><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></span></div>
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</div>
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</td>
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<td>浮点除法运算的余数<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-math-remainder.html"><span class="t-lines"><span>remainder</span><span>remainderf</span><span>remainderl</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><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>除法运算的有符号余数<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-math-remquo.html"><span class="t-lines"><span>remquo</span><span>remquof</span><span>remquol</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><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
|
|
</td>
|
|
<td>除法运算的有符号余数和最后三个二进制位<br />
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<span class="t-mark">(函数)</span></td>
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|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
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|
</body>
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|
</html>
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