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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!-- but may not be published or retransmitted without explicit permission.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/scanfinterlace.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 12.18a</title><link href="scanfhang.html" rev=precedes><link href="scanfc.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="scanfhang.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="scanfc.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 12.18a</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>I'm reading a number with <TT>scanf</TT>and<TT>%d</TT>,and then a string with<TT>gets()</TT>:<pre> int n; char str[80]; printf("enter a number: "); scanf("%d", &n); printf("enter a string: "); gets(str); printf("you typed %d and \"%s\"\n", n, str);</pre>but the compiler seems to beskipping the call to <TT>gets()</TT>!</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>If, in response to the above program,you type the two lines<pre> 42 a string</pre><TT>scanf</TT> will read the 42,but <em>not</em> the newline following it.That newline will remain on the input stream,where it will immediately satisfy <TT>gets()</TT>(which willthereforeseem toreada blank line).The second line,``a string'',will not be read at all.</p><p>If you had happened to typeboth the number and the stringon the same line:<pre> 42 a string</pre>the codewould have worked more or less as you expected.</p><p>As a general rule,you shouldn't try tointerlacecalls to <TT>scanf</TT> with calls to <TT>gets()</TT>(or any other input routines);<TT>scanf</TT>'s peculiar treatment of newlinesalmostalwaysleads totrouble.Either use <TT>scanf</TT> to read everythingor nothing.</p><p>See also questions<a href="scanfprobs.html">12.20</a>and<a href="getsvsfgets.html">12.23</a>.</p><p>Additional links:<a href="gets_flush2.html">longer explanation</a></p><p>References:ISO Sec. 7.9.6.2<br>H&S Sec. 15.8 pp. 357-64<br></p><!-- aend --><p><hr><a href="scanfhang.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="scanfc.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/scanfinterlace.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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