📄 nonconstcase.html
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN"><!-- This collection of hypertext pages is Copyright 1995-2005 by Steve Summit. --><!-- Content from the book "C Programming FAQs: Frequently Asked Questions" --><!-- (Addison-Wesley, 1995, ISBN 0-201-84519-9) is made available here by --><!-- permission of the author and the publisher as a service to the community. --><!-- It is intended to complement the use of the published text --><!-- and is protected by international copyright laws. --><!-- The on-line content may be accessed freely for personal use --><!-- but may not be published or retransmitted without explicit permission. --><!-- --><!-- this page built Sat Dec 24 21:47:47 2005 by faqproc version 2.7 --><!-- from source file misclang.sgml dated Wed Dec 21 13:02:49 2005 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/misc/nonconstcase.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:05 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 20.18</title><link href="strswitch.html" rev=precedes><link href="returnparens.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="strswitch.html" rev=precedes><img src="../images/buttonleft.gif" alt="prev"></a><a href="index.html" rev=subdocument><img src="../images/buttonup.gif" alt="up"></a><a href="returnparens.html" rel=precedes><img src="../images/buttonright.gif" alt="next"></a> <a href="../index-2.html"><img src="../images/buttontop.gif" alt="top/contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><hr><p><!-- qbegin --><h1>comp.lang.c FAQ list<font color=blue>·</font><!-- qtag -->Question 20.18</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>Is there a way to have non-constant <TT>case</TT> labels(i.e. ranges or arbitrary expressions)?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>No.The <TT>switch</TT> statementwas originally designed to be quite simple for the compiler to translate,therefore case labels are limited to single, constant, integral expressions.You <em>can</em> attach several case labels to the same statement,which will let you cover a small range if you don't mind listing all cases explicitly.</p><p>If you want to select on arbitrary rangesor non-constant expressions,you'll have to use an <TT>if</TT>/<TT>else</TT> chain.</p><p>See alsoquestions <a href="switchimpl.html">20.16</a> and <a href="strswitch.html">20.17</a>.</p><p>References:K&R1 Sec. 3.4 p. 55<br>K&R2 Sec. 3.4 p. 58<br>ISO Sec. 6.6.4.2<br>Rationale Sec. 3.6.4.2<br>H&S Sec. 8.7 p. 248<br></p><!-- aend --><p><hr><a href="strswitch.html" rev=precedes><img src="../images/buttonleft.gif" alt="prev"></a><a href="index.html" rev=subdocument><img src="../images/buttonup.gif" alt="up"></a><a href="returnparens.html" rel=precedes><img src="../images/buttonright.gif" alt="next"></a> <a href="../questions.html"><img src="../images/buttontop.gif" alt="contents"></a><a href="../search.html"><img src="../images/buttonsrch.gif" alt="search"></a><br><!-- lastfooter --><a href="../about.html">about this FAQ list</a> <a href="../eskimo.html">about eskimo</a> <a href="../search.html">search</a> <a href="../feedback.html">feedback</a> <a href="copyright.html">copyright</a><p>Hosted by<a href="http://www.eskimo.com/"><img src="../../www.eskimo.com/img/link/eskitiny.gif" alt="Eskimo North"></a></body><!-- Mirrored from c-faq.com/misc/nonconstcase.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:05 GMT --></html>⌨️ 快捷键说明
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