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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!-- but may not be published or retransmitted without explicit permission.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 21:47:46 2005 by faqproc version 2.7 --><!-- from source file style.sgml dated Sat Jul 3 17:22:13 2004 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/style/voidcasts.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:01 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 17.5</title><link href="protomacro.html" rev=precedes><link href="nullor0.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="protomacro.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="nullor0.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 17.5</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>I came across some code thatputsa <TT>(void)</TT> cast beforeeachcall to <TT>printf</TT>.Why?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font><TT>printf</TT>does return a value(the number of characters printed,or an error code),though few programsbother tocheck the return values from each call.Since some compilers(and <TT>lint</TT>)will warn about discarded return values,an explicit cast to <TT>(void)</TT> is a way of saying``Yes,I've decided to ignore the return value from this call,but please continue to warn me about other(perhaps inadvertently)ignored return values.''It's also common to use<TT>void</TT> castson calls to <TT>strcpy</TT> and <TT>strcat</TT>,since the return value isnever surprising.</p><p>References:K&R2 Sec. A6.7 p. 199<br>Rationale Sec. 3.3.4<br>H&S Sec. 6.2.9 p. 172, Sec. 7.13 pp. 229-30<br></p><!-- aend --><p><hr><a href="protomacro.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="nullor0.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/style/voidcasts.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:01 GMT --></html>⌨️ 快捷键说明
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