1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>switch_ Statement</title> 5<link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../index.html" title="Chapter 1. Phoenix 3.2.0"> 8<link rel="up" href="../statement.html" title="Statement"> 9<link rel="prev" href="___if_else_____statement.html" title="if_else_ Statement"> 10<link rel="next" href="while__statement.html" title="while_ Statement"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="___if_else_____statement.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../statement.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="while__statement.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="phoenix.modules.statement.switch__statement"></a><a class="link" href="switch__statement.html" title="switch_ Statement">switch_ 28 Statement</a> 29</h4></div></div></div> 30<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">phoenix</span><span class="special">/</span><span class="identifier">statement</span><span class="special">/</span><span class="keyword">switch</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 31</pre> 32<p> 33 The syntax is: 34 </p> 35<pre class="programlisting"><span class="identifier">switch_</span><span class="special">(</span><span class="identifier">integral_expression</span><span class="special">)</span> 36<span class="special">[</span> 37 <span class="identifier">case_</span><span class="special"><</span><span class="identifier">integral_value</span><span class="special">>(</span><span class="identifier">sequenced_statements</span><span class="special">),</span> 38 <span class="special">...</span> 39 <span class="identifier">default_</span><span class="special">(</span><span class="identifier">sequenced_statements</span><span class="special">)</span> 40<span class="special">]</span> 41</pre> 42<p> 43 A comma separated list of cases, and an optional default can be provided. 44 Note unlike a normal switch statement, cases do not fall through. 45 </p> 46<p> 47 Example: This code prints out <code class="computeroutput"><span class="string">"one"</span></code>, 48 <code class="computeroutput"><span class="string">"two"</span></code> or <code class="computeroutput"><span class="string">"other value"</span></code> depending on the 49 element's actual value: 50 </p> 51<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">for_each</span><span class="special">(</span><span class="identifier">c</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">c</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> 52 <span class="identifier">switch_</span><span class="special">(</span><span class="identifier">arg1</span><span class="special">)</span> 53 <span class="special">[</span> 54 <span class="identifier">case_</span><span class="special"><</span><span class="number">1</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">val</span><span class="special">(</span><span class="string">"one"</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">),</span> 55 <span class="identifier">case_</span><span class="special"><</span><span class="number">2</span><span class="special">>(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">val</span><span class="special">(</span><span class="string">"two"</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">),</span> 56 <span class="identifier">default_</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">val</span><span class="special">(</span><span class="string">"other value"</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">)</span> 57 <span class="special">]</span> 58<span class="special">);</span> 59</pre> 60</div> 61<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 62<td align="left"></td> 63<td align="right"><div class="copyright-footer">Copyright © 2002-2005, 2010, 2014, 2015 Joel de Guzman, Dan Marsden, Thomas 64 Heller, John Fletcher<p> 65 Distributed under the Boost Software License, Version 1.0. (See accompanying 66 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 67 </p> 68</div></td> 69</tr></table> 70<hr> 71<div class="spirit-nav"> 72<a accesskey="p" href="___if_else_____statement.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../statement.html"><img src="../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="while__statement.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 73</div> 74</body> 75</html> 76
