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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!-- but may not be published or retransmitted without explicit permission.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 stdio.sgml dated Wed Dec 21 13:07:57 2005 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/stdio/printfpercent.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:57 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 12.6</title><link href="charatatime.html" rev=precedes><link href="printftypes.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="charatatime.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="printftypes.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 12.6</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>How can I print a <TT>'%'</TT> characterin a <TT>printf</TT> format string?I tried <TT>\%</TT>, but it didn't work.</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>Simply double the percent sign:<TT>%%</TT> .</p><p>The reason it's tricky to print <TT>%</TT> signs with <TT>printf</TT>is that <TT>%</TT> is essentially <TT>printf</TT>'sescape character.Whenever <TT>printf</TT> sees a <TT>%</TT>,it expects it to be followed by a character telling it what to do next.The two-character sequence <TT>%%</TT>is definedtoprint a single <TT>%</TT>.</p><p>To understand why<TT>\%</TT> can't work,rememberthatthe backslash <TT>\</TT>is the <em>compiler's</em> escape character,andcontrols how the compiler interprets source code charactersat compile time.In this case,however,we want to control how <TT>printf</TT> interprets its format stringat run-time.As far as the compiler is concerned,the escape sequence <TT>\%</TT> is undefined,and probably results in a single <TT>%</TT> character.It would be unlikely for both the <TT>\</TT> and the <TT>%</TT> tomake itthrough to <TT>printf</TT>,even if <TT>printf</TT> were prepared totreatthe <TT>\</TT>specially.</p><p>Additional links:<a href="cescapes.html">further reading</a></p><p>See alsoquestions <a href="../charstring/runtimesc.html">8.8</a> and <a href="../osdep/dospath.html">19.17</a>.</p><p>References:K&R1 Sec. 7.3 p. 147<br>K&R2 Sec. 7.2 p. 154<br>ISO Sec. 7.9.6.1<br></p><!-- aend --><p><hr><a href="charatatime.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="printftypes.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/stdio/printfpercent.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:57 GMT --></html>⌨️ 快捷键说明
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