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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!-- but may not be published or retransmitted without explicit permission.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/eofval.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 12.1b</title><link href="getcharc.html" rev=precedes><link href="feof.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="getcharc.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="feof.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 12.1b</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>I have a simple little program that reads characters until EOF,but how do I actually <em>enter</em> that ``EOF'' valuefrom the keyboard?I see that <TT>EOF</TT> is defined by <TT><stdio.h></TT> to be -1;am I supposed to enter -1?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>If you think about it,what you enter <em>can't</em> be -1,because ``-1'' is two characters,and <TT>getchar</TT> is reading one character at a time.It turns out that the value of EOF as seen within your C programhas essentially nothing to do with the keystroke combination youmightuse to signal end-of-file from the keyboard.EOF is essentially a signal to your programthat no more characterswill be availablefrom that input,for <em>whatever</em> reason(end of a disk file,user is done typing,network stream has closed,I/O error, etc.).</p><p>Depending on your operating system,you indicate end-of-filefrom the keyboardusing various keystroke combinations,usually either control-D or control-Z.The operating system and stdio library then arrangethat your C program receive the EOF value.(Note, however, that there are various translations involved along the way.Under normal circumstances,you should <em>not</em> explicitly check forthe control-D or control-Z value yourself,nor will you find thatthe <TT><stdio.h></TT> macro<TT>EOF</TT> is defined to be either of these values.)</p><!-- aend --><p><hr><a href="getcharc.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="feof.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/eofval.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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