873 lines
57 KiB
HTML
873 lines
57 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>算术运算符</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_language_operator_arithmetic skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading">算术运算符</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-language.html">language</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<p>算术运算符应用标准数学运算符到其操作数。</p>
|
|
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
|
|
<tr>
|
|
<td class="mbox-empty-cell"></td>
|
|
<td class="mbox-text" style="">本节未完成<br />
|
|
原因：为这个和其他表格考虑更通用的，覆盖多个专题的 ToC</td>
|
|
</tr>
|
|
</table>
|
|
<table class="wikitable" style="font-size:85%;">
|
|
<tr style="text-align:center">
|
|
<th>运算符</th>
|
|
<th>运算符名</th>
|
|
<th>示例</th>
|
|
<th>结果</th>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">+</span></span></span></td>
|
|
<td>一元加</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">+</span>a</span></span></td>
|
|
<td><b>a</b> 提升后的值</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">-</span></span></span></td>
|
|
<td>一元减</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">-</span>a</span></span></td>
|
|
<td><b>a</b> 的相反数</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">+</span></span></span></td>
|
|
<td>加法</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy2">+</span> b</span></span></td>
|
|
<td><b>a</b> 加 <b>b</b></td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">-</span></span></span></td>
|
|
<td>减法</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy2">-</span> b</span></span></td>
|
|
<td>从 <b>a</b> 减去 <b>b</b></td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">*</span></span></span></td>
|
|
<td>乘法</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy2">*</span> b</span></span></td>
|
|
<td><b>a</b> 和 <b>b</b> 的积</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">/</span></span></span></td>
|
|
<td>除法</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy2">/</span> b</span></span></td>
|
|
<td><b>a</b> 除以 <b>b</b> 的商</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">%</span></span></span></td>
|
|
<td>模</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy2">%</span> b</span></span></td>
|
|
<td><b>a</b> 除以 <b>b</b> 的余数</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">~</span></span></td>
|
|
<td>逐位非</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">~a</span></span></td>
|
|
<td><b>a</b> 的逐位非</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy3">&</span></span></span></td>
|
|
<td>逐位与</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy3">&</span> b</span></span></td>
|
|
<td><b>a</b> 和 <b>b</b> 的逐位与</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy3">|</span></span></span></td>
|
|
<td>逐位或</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy3">|</span> b</span></span></td>
|
|
<td><b>a</b> 和 <b>b</b> 的逐位或</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy3">^</span></span></span></td>
|
|
<td>逐位异或</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy3">^</span> b</span></span></td>
|
|
<td><b>a</b> 和 <b>b</b> 的逐位异或</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy1"><<</span></span></span></td>
|
|
<td>逐位左移</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy1"><<</span> b</span></span></td>
|
|
<td><b>a</b> 左移 <b>b</b> 位</td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><span class="t-c"><span class="mw-geshi c source-c"><span class="sy1">>></span></span></span></td>
|
|
<td>逐位右移</td>
|
|
<td><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy1">>></span> b</span></span></td>
|
|
<td><b>a</b> 右移 <b>b</b> 位</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E6.BA.A2.E5.87.BA">溢出</span></h3>
|
|
<p>无符号整数算术始终进行 <span class="texhtml" style="white-space: nowrap;">modulo 2<span class="t-su">n<br /></span></span> ，其中 n 是该特定整数中的位数。例如对于 <span class="t-c"><span class="mw-geshi c source-c"><span class="kw4">unsigned</span> <span class="kw4">int</span></span></span> ，加一到 <span class="t-lc"><a href="c-types-limits.html">UINT_MAX</a></span> 给出 <span class="t-c"><span class="mw-geshi c source-c">​<span class="nu0">0</span>​</span></span> ，而从 <span class="t-c"><span class="mw-geshi c source-c">​<span class="nu0">0</span>​</span></span> 减一给出 <span class="t-lc"><a href="c-types-limits.html">UINT_MAX</a></span> 。</p>
|
|
<p>有符号算术运算溢出（结果不符合结果类型）时，行为未定义：可以按照表示（典型为补码）的规则回卷，可以在某些平台上或由于编译器选项（例如 gcc 和 clang 中的 <code>-ftrapv</code> ）陷落，或完全<a rel="nofollow" class="external text" href="http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html">被编译器优化掉</a>。</p>
|
|
<h4><span class="mw-headline" id=".E6.B5.AE.E7.82.B9.E7.8E.AF.E5.A2.83">浮点环境</span></h4>
|
|
<p>若设置 <a href="c-preprocessor-impl.html"><tt>#pragma STDC FENV_ACCESS</tt></a> 为 <code>ON</code> ，则所有浮点算术运算符遵循当前浮点<a href="c-numeric-fenv-FE_round.html">舍入方向</a>并报告 <a href="c-numeric-math-math_errhandling.html"><tt>math_errhandling</tt></a> 中指定的错误，除非它们是<a href="c-language-initialization.html">静态初始化器</a>的一部分（该情况下不引发浮点异常，而舍入模式为到最接近）。</p>
|
|
<h4><span class="mw-headline" id=".E6.B5.AE.E7.82.B9.E7.BC.A9.E7.95.A5">浮点缩略</span></h4>
|
|
<p>除非设置 <a href="c-preprocessor-impl.html"><tt>#pragma STDC FP_CONTRACT</tt></a> 为 <code>OFF</code> ，否则可能如同中间结果拥有无限范围和精度一般进行所有浮点算术，这种优化省略若准确按写法求值表达式，则会观察到的舍入误差和浮点异常。例如，允许以单条融合乘加 CPU 指令实现 <span class="t-c"><span class="mw-geshi c source-c"><span class="br0">(</span>x<span class="sy2">*</span>y<span class="br0">)</span> <span class="sy2">+</span> z</span></span> ，或把 <span class="t-c"><span class="mw-geshi c source-c">a <span class="sy1">=</span> x<span class="sy2">*</span>x<span class="sy2">*</span>x<span class="sy2">*</span>x<span class="sy4">;</span></span></span> 优化成 <span class="t-c"><span class="mw-geshi c source-c">tmp <span class="sy1">=</span> x<span class="sy2">*</span>x<span class="sy4">;</span> a <span class="sy1">=</span> tmp<span class="sy2">*</span>tmp</span></span> 。</p>
|
|
<p>与缩略无关，浮点算术的中间结果可以拥有异于其类型所指定的范围和精度，见 <span class="t-lc"><a href="c-types-limits-FLT_EVAL_METHOD.html">FLT_EVAL_METHOD</a></span> 。</p>
|
|
<h3><span class="mw-headline" id=".E4.B8.80.E5.85.83.E7.AE.97.E6.9C.AF">一元算术</span></h3>
|
|
<p>一元算术运算符表达式拥有形式</p>
|
|
<table class="t-sdsc-begin">
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><code><b>+</b></code> <span class="t-spar">expression</span></td>
|
|
<td>(1)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><code><b>-</b></code> <span class="t-spar">expression</span></td>
|
|
<td>(2)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 一元加（提升）</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 一元减（相反数）
|
|
<p>where</p>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td><span class="t-spar">expression</span></td>
|
|
<td>-</td>
|
|
<td>任何<a href="c-language-arithmetic_types.html">算术类型</a>表达式</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<p>一元加和一元减都首先应用<a href="c-language-conversion.html">整数提升</a>到其操作数，然后</p>
|
|
<ul>
|
|
<li>一元加返回提升后的值</li>
|
|
<li>一元减返回提升后值的相反数（除了 NaN 的相反数是另一 NaN ）</li>
|
|
</ul>
|
|
<p>表达式类型为提升后的类型，而<a href="c-language-value_category.html">值类别</a>为非左值。</p>
|
|
<h4><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h4>
|
|
<p>在典型（补码）平台上应用到 <span class="t-lc"><a href="c-types-limits.html">INT_MIN</a></span> 、 <span class="t-lc"><a href="c-types-limits.html">LONG_MIN</a></span> 或 <span class="t-lc"><a href="c-types-limits.html">LLONG_MIN</a></span> 时，一元减引起有符号整数溢出所致的未定义行为。</p>
|
|
<p>C++ 中一元运算符 + 亦能用于其他内建类型，例如数组和函数，但 C 中不能。</p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#include <stdio.h></span>
|
|
<span class="co2">#include <complex.h></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">char</span> c <span class="sy1">=</span> <span class="st0">'a'</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"sizeof char: %zu sizeof int: %zu<span class="es1">\n</span>"</span>, <span class="kw4">sizeof</span> c, <span class="kw4">sizeof</span> <span class="sy2">+</span>c<span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"-1, where 1 is signed: %d<span class="es1">\n</span>"</span>, <span class="sy2">-</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"-1, where 1 is unsigned: %u<span class="es1">\n</span>"</span>, <span class="sy2">-</span>1u<span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<span class="kw4">double</span> <a href="c-numeric-complex-complex.html"><span class="kw743">complex</span></a> z <span class="sy1">=</span> <span class="nu0">1</span> <span class="sy2">+</span> <span class="nu0">2</span><span class="sy2">*</span>I<span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"-(1+2i) = %.1f%+.1f<span class="es1">\n</span>"</span>, <a href="c-numeric-complex-creal.html"><span class="kw754">creal</span></a><span class="br0">(</span><span class="sy2">-</span>z<span class="br0">)</span>, <a href="c-numeric-complex-cimag.html"><span class="kw751">cimag</span></a><span class="br0">(</span><span class="sy2">-</span>z<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">sizeof char: 1 sizeof int: 4
|
|
-1, where 1 is signed: -1
|
|
-1, where 1 is unsigned: 4294967295
|
|
-(1+2i) = -1.0-2.0</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8A.A0.E6.B3.95.E6.80.A7.E8.BF.90.E7.AE.97.E7.AC.A6">加法性运算符</span></h3>
|
|
<p>下列加法性算术运算符拥有形式</p>
|
|
<table class="t-sdsc-begin">
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>+</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(1)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>-</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(2)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 加法： <span class="t-spar">lhs</span> 与 <span class="t-spar">rhs</span> 必须为下列之一
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>都拥有<a href="c-language-arithmetic_types.html">算术类型</a>，包含复数和虚数</li>
|
|
<li>一个是指向完整对象的指针类型，另一个拥有整数类型</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 减法： <span class="t-spar">lhs</span> 与 <span class="t-spar">rhs</span> 必须为下列之一
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>都拥有<a href="c-language-arithmetic_types.html">算术类型</a>，包含复数和虚数</li>
|
|
<li><span class="t-spar">lhs</span> 拥有指向完整对象的指针类型， <span class="t-spar">rhs</span> 拥有整数类型</li>
|
|
<li>都是指向拥有<a href="c-language-types.html#.E5.85.BC.E5.AE.B9.E7.B1.BB.E5.9E.8B">兼容</a>类型的完整对象指针，忽略限定符</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
</div>
|
|
<h4><span class="mw-headline" id=".E7.AE.97.E6.9C.AF.E5.8A.A0.E6.B3.95.E4.B8.8E.E5.87.8F.E6.B3.95">算术加法与减法</span></h4>
|
|
<p>若两个操作数都拥有<a href="c-language-arithmetic_types.html">算术类型</a>，则</p>
|
|
<ul>
|
|
<li>首先，进行<a href="c-language-conversion.html#.E9.80.9A.E5.B8.B8.E7.AE.97.E6.9C.AF.E8.BD.AC.E6.8D.A2">通常算术转换</a></li>
|
|
<li>然后，遵循数学规则，加或减操作数在提升后的值（对于减法，从 <span class="t-spar">lhs</span> 减去 <span class="t-spar">rhs</span> ），除了</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>若操作数之一为 NaN ，则结果为 NaN</li>
|
|
<li>同号无穷大减无穷大为 NaN 并引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span></li>
|
|
<li>正无穷大加负无穷大为 NaN 并引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span></li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<p>复数和虚数加减法定义如下（注意若两个操作数均为虚数则结果类型为虚数，而若一个操作数为实数而另一为虚数，则结果为复数，同通常算术转换所指定）：</p>
|
|
<table class="wikitable" style="text-align:center; font-size:85%; max-width:90em;">
|
|
<tr>
|
|
<th>+ or -</th>
|
|
<th>u</th>
|
|
<th>iv</th>
|
|
<th>u + iv</th>
|
|
</tr>
|
|
<tr>
|
|
<th>x</th>
|
|
<td>x ± u</td>
|
|
<td>x ± iv</td>
|
|
<td>(x ± u) ± iv</td>
|
|
</tr>
|
|
<tr>
|
|
<th>iy</th>
|
|
<td>±u + iy</td>
|
|
<td>i(y ± v)</td>
|
|
<td>±u + i(y ± v)</td>
|
|
</tr>
|
|
<tr>
|
|
<th>x + iy</th>
|
|
<td>(x ± u) + iy</td>
|
|
<td>x + i(y ± v)</td>
|
|
<td>(x ± u) + i(y ± v)</td>
|
|
</tr>
|
|
</table>
|
|
<p><br /></p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co1">// 工作中</span>
|
|
<span class="co1">// 注意：采用 c/language/conversion 示例的一部分</span></pre></div>
|
|
</div>
|
|
</div>
|
|
<h4><span class="mw-headline" id=".E6.8C.87.E9.92.88.E7.AE.97.E6.9C.AF">指针算术</span></h4>
|
|
<ul>
|
|
<li>若指针 <code>P</code> 指向下标为 <code>I</code> 的数组元素，则</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li><span class="t-c"><span class="mw-geshi c source-c">P<span class="sy2">+</span>N</span></span> 与 <span class="t-c"><span class="mw-geshi c source-c">N<span class="sy2">+</span>P</span></span> 是指向同一数组中下标为 <code>I+N</code> 的元素的指针</li>
|
|
<li><span class="t-c"><span class="mw-geshi c source-c">P<span class="sy2">-</span>N</span></span> 是指向同一数组中下标为 <code>I-N</code> 的元素的指针</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<p>仅若原指针和结果指针都指向同一数组中的元素，或该数组的尾后一位置，行为才有定义。注意在 p 指向数组首元素时，执行 p-1 是未定义行为，并且在某些平台上可能失败。</p>
|
|
<ul>
|
|
<li>若指针 <code>P1</code> 指向下标为 <code>I</code> 的数组元素（或尾后一位置）而 <code>P2</code> 是指向同一数组的下标为 <code>J</code> 的元素（或尾后一位置），则</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li><span class="t-c"><span class="mw-geshi c source-c">P1<span class="sy2">-</span>P2</span></span> 拥有等于 <span class="t-c"><span class="mw-geshi c source-c">I<span class="sy2">-</span>J</span></span> 的值和 <span class="t-lc"><a href="c-types-ptrdiff_t.html">ptrdiff_t</a></span> 类型（有符号整数类型，最大大小典型地为能声明的最大对象的一半）</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<p>仅若结果适合于 <span class="t-lc"><a href="c-types-ptrdiff_t.html">ptrdiff_t</a></span> ，行为才有定义。</p>
|
|
<p>为指针算术的目的，把指向非数组元素的对象的指针当做指向大小为 1 的数组首元素的指针。</p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co1">// 工作中</span>
|
|
<span class="kw4">int</span> n <span class="sy1">=</span> <span class="nu0">4</span>, m <span class="sy1">=</span> <span class="nu0">3</span><span class="sy4">;</span>
|
|
<span class="kw4">int</span> a<span class="br0">[</span>n<span class="br0">]</span><span class="br0">[</span>m<span class="br0">]</span><span class="sy4">;</span> <span class="co1">// 4 个 VLA 的 VLA ，每个有 3 个 int</span>
|
|
<span class="kw4">int</span> <span class="br0">(</span><span class="sy2">*</span>p<span class="br0">)</span><span class="br0">[</span>m<span class="br0">]</span> <span class="sy1">=</span> a<span class="sy4">;</span> <span class="co1">// p == &a[0] </span>
|
|
p <span class="sy1">=</span> p <span class="sy2">+</span> <span class="nu0">1</span><span class="sy4">;</span> <span class="co1">// p == &a[1] （ VLA 所用的指针算术一如平常）</span>
|
|
<span class="br0">(</span><span class="sy2">*</span>p<span class="br0">)</span><span class="br0">[</span><span class="nu0">2</span><span class="br0">]</span> <span class="sy1">=</span> <span class="nu0">99</span><span class="sy4">;</span> <span class="co1">// 更改 a[1][2]</span></pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E4.B9.98.E6.B3.95.E6.80.A7.E8.BF.90.E7.AE.97.E7.AC.A6">乘法性运算符</span></h3>
|
|
<p>下列乘法性运算符拥有形式</p>
|
|
<table class="t-sdsc-begin">
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>*</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(1)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>/</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(2)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>%</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(3)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 乘法。 <span class="t-spar">lhs</span> 与 <span class="t-spar">rhs</span> 必须拥有<a href="c-language-arithmetic_types.html">算术类型</a></div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 除法。 <span class="t-spar">lhs</span> 与 <span class="t-spar">rhs</span> 必须拥有<a href="c-language-arithmetic_types.html">算术类型</a></div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 余数。 <span class="t-spar">lhs</span> 与 <span class="t-spar">rhs</span> 必须拥有<a href="c-language-arithmetic_types.html">整数类型</a></div>
|
|
<ul>
|
|
<li>首先，进行<a href="c-language-conversion.html#.E9.80.9A.E5.B8.B8.E7.AE.97.E6.9C.AF.E8.BD.AC.E6.8D.A2">通常算术转换</a>。然后……</li>
|
|
</ul>
|
|
<h4><span class="mw-headline" id=".E4.B9.98.E6.B3.95">乘法</span></h4>
|
|
<p>二元运算符 * 遵循通常算术定义，进行其操作数（在通常算术提升后）的乘法，除了</p>
|
|
<ul>
|
|
<li>若操作数之一为 NaN ，则结果为 NaN</li>
|
|
<li>无穷大乘零给出 NaN 并引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span></li>
|
|
<li>无穷大乘非零给出无穷大（即使对于复参数）</li>
|
|
</ul>
|
|
<p>因为 C 中，任何带至少一个无穷大部分的<a href="c-language-arithmetic_types.html">复数值</a>为无穷大，即使另一部分为 NaN ，故通常算术规则不应用于复复乘法。其他浮点操作数的组合遵循下表：</p>
|
|
<table class="wikitable" style="text-align:center; font-size:85%; max-width:90em;">
|
|
<tr>
|
|
<th>*</th>
|
|
<th>u</th>
|
|
<th>iv</th>
|
|
<th>u + iv</th>
|
|
</tr>
|
|
<tr>
|
|
<th>x</th>
|
|
<td>xu</td>
|
|
<td>i(xv)</td>
|
|
<td>(xu) + i(xv)</td>
|
|
</tr>
|
|
<tr>
|
|
<th>iy</th>
|
|
<td>i(yu)</td>
|
|
<td>−yv</td>
|
|
<td>(−yv) + i(yu)</td>
|
|
</tr>
|
|
<tr>
|
|
<th>x + iy</th>
|
|
<td>(xu) + i(yu)</td>
|
|
<td>(−yv) + i(xv)</td>
|
|
<td><i>special rules</i></td>
|
|
</tr>
|
|
</table>
|
|
<p>在无穷大处理外，不允许复数乘法上溢中间结果，除了在设置 <a href="c-preprocessor-impl.html"><tt>#pragma STDC CX_LIMITED_RANGE</tt></a> 为 <code>ON</code> 时，该情况下可以如同 <span class="texhtml" style="white-space: nowrap;">(x+iy)×(u+iv) = (xu-yv)+i(yu+xv)</span> 一般计算值，因为假定了程序员负责限制操作数的范围并处理无穷大。</p>
|
|
<p>虽然不允许过度的上溢，复数乘法可能引发虚假的浮点异常（否则实现不上溢版本困难到近乎不可能）。</p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#include<stdio.h></span>
|
|
<span class="co2">#include <stdio.h></span>
|
|
<span class="co2">#include <complex.h></span>
|
|
<span class="co2">#include <math.h></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
|
|
|
|
<span class="co1">// TODO 从 C++ 采取一些更简单的情况</span>
|
|
|
|
|
|
<span class="kw4">double</span> <a href="c-numeric-complex-complex.html"><span class="kw743">complex</span></a> z <span class="sy1">=</span> <span class="br0">(</span><span class="nu0">1</span> <span class="sy2">+</span> <span class="nu0">0</span><span class="sy2">*</span>I<span class="br0">)</span> <span class="sy2">*</span> <span class="br0">(</span>INFINITY <span class="sy2">+</span> I<span class="sy2">*</span>INFINITY<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="co1">// 教科书公式会给出</span>
|
|
<span class="co1">// (1+i0)(∞+i∞) ⇒ (1×∞ – 0×∞) + i(0×∞+1×∞) ⇒ NaN + I*NaN</span>
|
|
<span class="co1">// 但 C 给出复无穷大</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"%f + i*%f<span class="es1">\n</span>"</span>, <a href="c-numeric-complex-creal.html"><span class="kw754">creal</span></a><span class="br0">(</span>z<span class="br0">)</span>, <a href="c-numeric-complex-cimag.html"><span class="kw751">cimag</span></a><span class="br0">(</span>z<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<span class="co1">// 教科书公式会给出</span>
|
|
<span class="co1">// cexp(∞+iNaN) ⇒ exp(∞)×(cis(NaN)) ⇒ NaN + I*NaN</span>
|
|
<span class="co1">// 但 C 给出 ±∞+i*nan</span>
|
|
<span class="kw4">double</span> <a href="c-numeric-complex-complex.html"><span class="kw743">complex</span></a> y <span class="sy1">=</span> <a href="c-numeric-complex-cexp.html"><span class="kw769">cexp</span></a><span class="br0">(</span>INFINITY <span class="sy2">+</span> I<span class="sy2">*</span>NAN<span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"%f + i*%f<span class="es1">\n</span>"</span>, <a href="c-numeric-complex-creal.html"><span class="kw754">creal</span></a><span class="br0">(</span>y<span class="br0">)</span>, <a href="c-numeric-complex-cimag.html"><span class="kw751">cimag</span></a><span class="br0">(</span>y<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">inf + i*inf
|
|
inf + i*nan</pre></div>
|
|
</div>
|
|
</div>
|
|
<h4><span class="mw-headline" id=".E9.99.A4.E6.B3.95">除法</span></h4>
|
|
<p>二元运算符 / 遵循通常的算术定义，将第一操作数除以第二操作数（在通常算术转换后），除了</p>
|
|
<ul>
|
|
<li>通常算术提升后的类型为整数类型时，结果为代数商（非分数），<span class="t-rev-inl t-until-c99"><span>以实现定义方向取整</span> <span><span class="t-mark-rev t-until-c99">(C99 前)</span></span></span><span class="t-rev-inl t-since-c99"><span>向零截断</span> <span><span class="t-mark-rev t-since-c99">(C99 起)</span></span></span></li>
|
|
<li>若操作数之一为 NaN ，则结果为 NaN</li>
|
|
<li>若第一操作数为复无穷大，而第二操作数为有限，则 / 运算符的结果为复无穷大</li>
|
|
<li>若第一操作数为有限而第二操作数为复无穷大，则 / 运算符的结果为零</li>
|
|
</ul>
|
|
<p>因为 C 中，任何带至少一个无穷大部分的<a href="c-language-arithmetic_types.html">复数值</a>为无穷大，即使另一部分为 NaN ，故通常算术规则不应用于复复除法。其他浮点操作数的组合遵循下表：</p>
|
|
<table class="wikitable" style="text-align:center; font-size:85%; max-width:90em;">
|
|
<tr>
|
|
<th>/</th>
|
|
<th>u</th>
|
|
<th>iv</th>
|
|
</tr>
|
|
<tr>
|
|
<th>x</th>
|
|
<td>x/u</td>
|
|
<td>i(−x/v)</td>
|
|
</tr>
|
|
<tr>
|
|
<th>iy</th>
|
|
<td>i(y/u)</td>
|
|
<td>y/v</td>
|
|
</tr>
|
|
<tr>
|
|
<th>x + iy</th>
|
|
<td>(x/u) + i(y/u)</td>
|
|
<td>(y/v) + i(−x/v)</td>
|
|
</tr>
|
|
</table>
|
|
<p>在无穷大处理外，不允许复数除法上溢中间结果，除了在设置 <a href="c-preprocessor-impl.html"><tt>#pragma STDC CX_LIMITED_RANGE</tt></a> 为 <code>ON</code> 时，该情况下可以如同 <span class="texhtml" style="white-space: nowrap;">(x+iy)/(u+iv) = [(xu+yv)+i(yu-xv)]/(u<span class="t-su">2<br /></span>+v<span class="t-su">2<br /></span>)</span> 一般计算值，因为假定了程序员负责限制操作数的范围并处理无穷大。</p>
|
|
<p>虽然不允许过度的上溢，复数除法可能引发虚假的浮点异常（否则实现不上溢版本困难到近乎不可能）。</p>
|
|
<p>若第二操作数为零，则行为未定义，除非支持 IEE 浮点算术，且发生浮点除法，则</p>
|
|
<ul>
|
|
<li>非零数除以 ±0.0 给出符号正确的无穷大并引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_DIVBYZERO</a></span></li>
|
|
<li>0.0 除以 0.0 给出 NaN 并引发 <span class="t-lc"><a href="c-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span></li>
|
|
</ul>
|
|
<h4><span class="mw-headline" id=".E4.BD.99.E6.95.B0">余数</span></h4>
|
|
<p>二元运算符 % 产出第一操作数除以第二操作数（在通常算术转换后）的余数。</p>
|
|
<p>余数的符号定义，使得若商 <code>a/b</code> 能以结果类型表示，则 <span class="t-c"><span class="mw-geshi c source-c"><span class="br0">(</span>a<span class="sy2">/</span>b<span class="br0">)</span><span class="sy2">*</span>b <span class="sy2">+</span> a<span class="sy2">%</span>b <span class="sy1">==</span> a</span></span> 。</p>
|
|
<p>若第二操作数为零，则行为未定义。</p>
|
|
<p>若商 <code>a/b</code> 不能以结果类型表示，则 <code>a/b</code> 和 <code>a%b</code> 的行为都未定义（这表明 <span class="t-c"><span class="mw-geshi c source-c">INT_MIN<span class="sy2">%-</span><span class="nu0">1</span></span></span> 在补码系统上未定义）。</p>
|
|
<p>注意：余数运算符不可用于浮点类型上，库函数 <span class="t-lc"><a href="c-numeric-math-fmod.html">fmod</a></span> 提供该功能。</p>
|
|
<h3><span class="mw-headline" id=".E9.80.90.E4.BD.8D.E9.80.BB.E8.BE.91">逐位逻辑</span></h3>
|
|
<p>逐位逻辑运算符拥有形式</p>
|
|
<table class="t-sdsc-begin">
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><code><b>~</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(1)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>&</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(2)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>|</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(3)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>^</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(4)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 逐位非</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 逐位与</div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 逐位或</div>
|
|
<div class="t-li1"><span class="t-li">4)</span> 逐位异或
|
|
<p>其中</p>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td><span class="t-spar">lhs</span>, <span class="t-spar">rhs</span></td>
|
|
<td>-</td>
|
|
<td>整数类型表达式</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<p>首先，运算符 & 、 ^ 和 | 在两个操作数上进行<a href="c-language-conversion.html#.E9.80.9A.E5.B8.B8.E7.AE.97.E6.9C.AF.E8.BD.AC.E6.8D.A2">通常算术转换</a>，而运算符 ~ 在其唯一的操作数上进行<a href="c-language-conversion.html#.E6.95.B4.E6.95.B0.E6.8F.90.E5.8D.87">整数提升</a>。</p>
|
|
<p>然后，逐位应用对应的逻辑运算符；即按照应用到操作数的每位的逻辑运算（或、与、非、异或），设置或清除结果的对应位。</p>
|
|
<p>注意：位运算符常用于操作位集和位掩码。</p>
|
|
<p>注意：对于无符号类型（提升后），表达式 ~E 等价于结果类型的最大可表示值减 E 的原值。</p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#include <stdio.h></span>
|
|
<span class="co2">#include <stdint.h></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<a href="c-types-integer.html"><span class="kw121">uint16_t</span></a> mask <span class="sy1">=</span> <span class="nu12">0x00f0</span><span class="sy4">;</span>
|
|
<a href="c-types-integer.html"><span class="kw122">uint32_t</span></a> a <span class="sy1">=</span> <span class="nu12">0x12345678</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"Value: %#x mask: %#x<span class="es1">\n</span>"</span>
|
|
<span class="st0">"Setting bits: %#x<span class="es1">\n</span>"</span>
|
|
<span class="st0">"Clearing bits: %#x<span class="es1">\n</span>"</span>
|
|
<span class="st0">"Selecting bits: %#x<span class="es1">\n</span>"</span>,
|
|
a,mask,<span class="br0">(</span>a<span class="sy3">|</span>mask<span class="br0">)</span>,<span class="br0">(</span>a<span class="sy3">&</span>~mask<span class="br0">)</span>,<span class="br0">(</span>a<span class="sy3">&</span>mask<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">Value: 0x12345678 mask: 0xf0
|
|
Setting bits: 0x123456f8
|
|
Clearing bits: 0x12345608
|
|
Selecting bits: 0x70</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E4.BD.8D.E7.A7.BB.E8.BF.90.E7.AE.97.E7.AC.A6">位移运算符</span></h3>
|
|
<p>位移运算符表达式拥有形式</p>
|
|
<table class="t-sdsc-begin">
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b><<</b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(1)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
<tr class="t-sdsc">
|
|
<td><span class="t-spar">lhs</span> <code><b>>></b></code> <span class="t-spar">rhs</span></td>
|
|
<td>(2)</td>
|
|
<td class="t-sdsc-nopad"></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="10" class="t-sdsc-sep"></td>
|
|
</tr>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> <span class="t-spar">lhs</span> 左移 <span class="t-spar">rhs</span> 位</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> <span class="t-spar">lhs</span> 右移 <span class="t-spar">rhs</span> 位
|
|
<p>其中</p>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td><span class="t-spar">lhs</span>, <span class="t-spar">rhs</span></td>
|
|
<td>-</td>
|
|
<td>整数类型表达式</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<p>首先，在每个操作数上独自进行<a href="c-language-conversion.html">整数提升</a>（注意：这不同于其他二元算术运算符，它们全都进行通常算术转换）。结果类型为 <span class="t-spar">lhs</span> 在提升后的类型。</p>
|
|
<p>对于无符号 <span class="t-spar">lhs</span> ， <code>LHS << RHS</code> 的值是 <span class="texhtml" style="white-space: nowrap;">LHS * 2<span class="t-su">RHS<br /></span></span> 以返回类型最大值加 1 取模（即进行逐位左移，并舍弃移出目标类型的位）。对于有非负值的有符号 <span class="t-spar">lhs</span> ，若值能以 <span class="t-spar">lhs</span> 的提升后类型表示，则 <code>LHS << RHS</code> 的值是 <span class="texhtml" style="white-space: nowrap;">LHS * 2<span class="t-su">RHS<br /></span></span> ，否则行为未定义。</p>
|
|
<p>对于无符号 <span class="t-spar">lhs</span> 和有非负值的有符号 <span class="t-spar">lhs</span> ， <code>LHS >> RHS</code> 的值是 <span class="texhtml" style="white-space: nowrap;">LHS / 2<span class="t-su">RHS<br /></span></span> 的整数部分。对于负的 <code>LHS</code> ， <code>LHS >> RHS</code> 的值是实现定义的，大多数实现中，这进行算术右移（故结果仍为负）。从而在大多数实现中，右移有符号的 <code>LHS</code> 会以原符号位填充新的高位（即若原数非负则为 0 ，而若原数为负则为 1 ）。</p>
|
|
<p>任何情况下，若 <span class="t-spar">rhs</span> 为负或大于或等于提升后的 <span class="t-spar">lhs</span> 中的位数，则行为未定义。</p>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="c source-c">
|
|
<pre class="de1"><span class="co2">#include <stdio.h></span>
|
|
<span class="kw2">enum</span> <span class="br0">{</span>ONE<span class="sy1">=</span><span class="nu0">1</span>, TWO<span class="sy1">=</span><span class="nu0">2</span><span class="br0">}</span><span class="sy4">;</span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">char</span> c <span class="sy1">=</span> <span class="nu12">0x10</span><span class="sy4">;</span>
|
|
<span class="kw4">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span> ulong_num <span class="sy1">=</span> <span class="nu12">0x123</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"0x123 << 1 = %#llx<span class="es1">\n</span>"</span>
|
|
<span class="st0">"0x123 << 63 = %#llx<span class="es1">\n</span>"</span> <span class="co1">// 对无符号数，溢出截断高位</span>
|
|
<span class="st0">"0x10 << 10 = %#x<span class="es1">\n</span>"</span>, <span class="co1">// char 被提升到 int</span>
|
|
ulong_num <span class="sy1"><<</span> <span class="nu0">1</span>, ulong_num <span class="sy1"><<</span> <span class="nu0">63</span>, c <span class="sy1"><<</span> <span class="nu0">10</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw4">long</span> <span class="kw4">long</span> long_num <span class="sy1">=</span> <span class="sy2">-</span><span class="nu0">1000</span><span class="sy4">;</span>
|
|
<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"-1000 >> 1 = %lld<span class="es1">\n</span>"</span>, long_num <span class="sy1">>></span> ONE<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 实现定义</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">0x123 << 1 = 0x246
|
|
0x123 << 63 = 0x8000000000000000
|
|
0x10 << 10 = 0x4000
|
|
-1000 >> 1 = -500</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
|
|
<div class="t-ref-std-11">
|
|
<ul>
|
|
<li>C11 标准（ISO/IEC 9899:2011）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.3.3 Unary arithmetic operators (p: 89)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.5 Multiplicative operators (p: 92)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.6 Additive operators (p: 92-94)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.7 Bitwise shift operators (p: 94-95)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.10 Bitwise AND operator (p: 97)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.11 Bitwise exclusive OR operator (p: 98)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.12 Bitwise inclusive OR operator (p: 98)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<div class="t-ref-std-c99">
|
|
<ul>
|
|
<li>C99 标准（ISO/IEC 9899:1999）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.3.3 Unary arithmetic operators (p: 79)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.5 Multiplicative operators (p: 82)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.6 Additive operators (p: 82-84)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.7 Bitwise shift operators (p: 84-85)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.10 Bitwise AND operator (p: 87)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.11 Bitwise exclusive OR operator (p: 88)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>6.5.12 Bitwise inclusive OR operator (p: 88)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<div class="t-ref-std-c89">
|
|
<ul>
|
|
<li>C89/C90 标准（ISO/IEC 9899:1990）：</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.3.3 Unary arithmetic operators</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.5 Multiplicative operators</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.6 Additive operators</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.7 Bitwise shift operators</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.10 Bitwise AND operator</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.11 Bitwise exclusive OR operator</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>3.3.12 Bitwise inclusive OR operator</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<p><a href="c-language-operator_precedence.html">运算符优先级</a></p>
|
|
<table class="wikitable">
|
|
<tr style="text-align:center">
|
|
<th colspan="7">常用运算符</th>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td><a href="c-language-operator_assignment.html">赋值</a></td>
|
|
<td><a href="c-language-operator_incdec.html">自增<br />
|
|
自减</a></td>
|
|
<td><strong class="selflink">算术</strong></td>
|
|
<td><a href="c-language-operator_logical.html">逻辑</a></td>
|
|
<td><a href="c-language-operator_comparison.html">比较</a></td>
|
|
<td><a href="c-language-operator_member_access.html">成员<br />
|
|
访问</a></td>
|
|
<td><a href="c-language-operator_other.html">其他</a></td>
|
|
</tr>
|
|
<tr style="text-align:center">
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy1">=</span> b<br />
|
|
a <span class="sy2">+</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy2">-</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy2">*</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy2">/</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy2">%</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy3">&</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy3">|</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy3">^</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy1"><<=</span> b<br />
|
|
a <span class="sy1">>>=</span> b</span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">++</span>a<br />
|
|
<span class="sy2">--</span>a<br />
|
|
a<span class="sy2">++</span><br />
|
|
a<span class="sy2">--</span></span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c"><span class="sy2">+</span>a<br />
|
|
<span class="sy2">-</span>a<br />
|
|
a <span class="sy2">+</span> b<br />
|
|
a <span class="sy2">-</span> b<br />
|
|
a <span class="sy2">*</span> b<br />
|
|
a <span class="sy2">/</span> b<br />
|
|
a <span class="sy2">%</span> b<br />
|
|
~a<br />
|
|
a <span class="sy3">&</span> b<br />
|
|
a <span class="sy3">|</span> b<br />
|
|
a <span class="sy3">^</span> b<br />
|
|
a <span class="sy1"><<</span> b<br />
|
|
a <span class="sy1">>></span> b</span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c"><span class="sy3">!</span>a<br />
|
|
a <span class="sy3">&&</span> b<br />
|
|
a <span class="sy3">||</span> b</span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c">a <span class="sy1">==</span> b<br />
|
|
a <span class="sy3">!</span><span class="sy1">=</span> b<br />
|
|
a <span class="sy1"><</span> b<br />
|
|
a <span class="sy1">></span> b<br />
|
|
a <span class="sy1"><=</span> b<br />
|
|
a <span class="sy1">>=</span> b</span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c">a<span class="br0">[</span>b<span class="br0">]</span><br />
|
|
<span class="sy2">*</span>a<br />
|
|
<span class="sy3">&</span>a<br />
|
|
a<span class="sy2">-</span><span class="sy1">></span>b<br />
|
|
a.<span class="me1">b</span></span></span></p>
|
|
</td>
|
|
<td>
|
|
<p><span class="t-c"><span class="mw-geshi c source-c">a<span class="br0">(</span>...<span class="br0">)</span><br />
|
|
a, b<br />
|
|
<span class="br0">(</span>type<span class="br0">)</span> a<br />
|
|
<span class="sy4">?</span> <span class="sy4">:</span><br />
|
|
<span class="kw4">sizeof</span><br />
|
|
_Alignof</span></span> <span class="t-mark-rev t-since-c11">(C11 起)</span></p>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<table class="t-dsc-begin"></table>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|