146 lines
9.8 KiB
HTML
146 lines
9.8 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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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>break 语句</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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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_language_break 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">break 语句</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-language.html">language</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<p>导致外围 <a href="c-language-for.html">for</a> 、 <a href="c-language-while.html">while</a> 或 <a href="c-language-do.html">do-while</a> 循环或 <a href="c-language-switch.html">switch 语句</a>终止。</p>
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<p>在用条件表达式和条件语句终止循环显得笨拙时使用。</p>
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<h3><span class="mw-headline" id=".E8.AF.AD.E6.B3.95">语法</span></h3>
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<table class="t-sdsc-begin">
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<tr>
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<td colspan="10" class="t-sdsc-sep"></td>
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</tr>
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<tr class="t-sdsc">
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<td class="t-sdsc-nopad"><span class="t-spar">属性说明符序列</span><span class="t-mark">(可选)</span> <code><b>break</b></code> <code><b>;</b></code></td>
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<td class="t-sdsc-nopad"></td>
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<td class="t-sdsc-nopad"></td>
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</tr>
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<tr>
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<td colspan="10" class="t-sdsc-sep"></td>
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</tr>
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</table>
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<table class="t-par-begin">
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<tr class="t-par">
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<td><span class="t-spar">属性说明符序列</span></td>
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<td>-</td>
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<td><span class="t-mark-rev t-since-c23">(C23)</span>可选的<a href="c-language-attributes.html">属性</a>列表,应用到 <code>break</code> 语句</td>
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</tr>
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</table>
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<p>只出现在循环体( <a href="c-language-while.html">while</a>、 <a href="c-language-do.html">do-while</a>、 <a href="c-language-for.html">for</a> )的 <span class="t-spar">语句</span> 内,或 <a href="c-language-switch.html">switch</a> 的 <span class="t-spar">语句</span> 内。</p>
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<h3><span class="mw-headline" id=".E8.A7.A3.E9.87.8A">解释</span></h3>
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<p>此语句后,控制被转移到紧随整个循环或 switch 之后的声明或语句,如同由 <a href="c-language-goto.html">goto</a> 进行。</p>
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<h3><span class="mw-headline" id=".E5.85.B3.E9.94.AE.E8.AF.8D">关键词</span></h3>
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<p><a href="c-keyword-break.html"><tt>break</tt></a></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><code>break</code> 语句不能用于打破多重嵌套循环。 <a href="c-language-goto.html">goto 语句</a>可用于此目的。</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="c source-c">
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<pre class="de1"><span class="co2">#include <stdio.h></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">int</span> i <span class="sy1">=</span> <span class="nu0">2</span><span class="sy4">;</span>
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<span class="kw1">switch</span> <span class="br0">(</span>i<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">case</span> <span class="nu0">1</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"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">case</span> <span class="nu0">2</span><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"2"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// i==2 ,故执行始于此 case 标号</span>
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<span class="kw1">case</span> <span class="nu0">3</span><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"3"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">case</span> <span class="nu0">4</span><span class="sy4">:</span>
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<span class="kw1">case</span> <span class="nu0">5</span><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"45"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">break</span><span class="sy4">;</span> <span class="co1">// 导致后续的 case 终止</span>
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<span class="kw1">case</span> <span class="nu0">6</span><span class="sy4">:</span> <a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"6"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 比较来自这二个循环嵌套的输出</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> j <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> j <span class="sy1"><</span> <span class="nu0">2</span><span class="sy4">;</span> j<span class="sy2">++</span><span class="br0">)</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> k <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> k <span class="sy1"><</span> <span class="nu0">5</span><span class="sy4">;</span> k<span class="sy2">++</span><span class="br0">)</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"%d%d "</span>, j,k<span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> j <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> j <span class="sy1"><</span> <span class="nu0">2</span><span class="sy4">;</span> j<span class="sy2">++</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> k <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> k <span class="sy1"><</span> <span class="nu0">5</span><span class="sy4">;</span> k<span class="sy2">++</span><span class="br0">)</span> <span class="br0">{</span> <span class="co1">// 只有此循环会由 break 退出</span>
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<span class="kw1">if</span> <span class="br0">(</span>k <span class="sy1">==</span> <span class="nu0">2</span><span class="br0">)</span> <span class="kw1">break</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw851">printf</span></a><span class="br0">(</span><span class="st0">"%d%d "</span>, j,k<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</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">2345
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00 01 02 03 04 10 11 12 13 14
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00 01 10 11</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-17">
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<ul>
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<li>C17 标准(ISO/IEC 9899:2018):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>6.8.6.3 The break statement (p: 111)</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准(ISO/IEC 9899:2011):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>6.8.6.3 The break statement (p: 153)</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-ref-std-c99">
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<ul>
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<li>C99 标准(ISO/IEC 9899:1999):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>6.8.6.3 The break statement (p: 138)</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-ref-std-c89">
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<ul>
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<li>C89/C90 标准(ISO/IEC 9899:1990):</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>3.6.6.3 The break statement</li>
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</ul>
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</dd>
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</dl>
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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"></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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</body>
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</html>
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