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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!-- but may not be published or retransmitted without explicit permission.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 osdepfile.sgml dated Sat Jun 26 20:52:13 2004 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/osdep/copy.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:02 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 19.16b</title><link href="delete.html" rev=precedes><link href="dospath.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="delete.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="dospath.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 19.16b</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>How do I copy files?</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>Either use <TT>system()</TT>to invoke your operating system's copy utility(see question <a href="system.html">19.27</a>),or openthe source and destination files(using <TT>fopen</TT> or some lower-level file-opening system call),read characters or blocks of characters from the source file,and write them to the destination file.Here is a simple example:<pre>#include <stdio.h>int copyfile(char *fromfile, char *tofile){ FILE *ifp, *ofp; int c; if((ifp = fopen(fromfile, "r")) == NULL) return -1; if((ofp = fopen(tofile, "w")) == NULL) { fclose(ifp); return -1; } while((c = getc(ifp)) != EOF) putc(c, ofp); fclose(ifp); fclose(ofp); return 0;}</pre>To copy a block at a time, rewrite the inner loop as<pre> while((r = fread(buf, 1, sizeof(buf), ifp)) > 0) fwrite(buf, 1, r, ofp);</pre>where <TT>r</TT> is an <TT>int</TT>and <TT>buf</TT> is a suitably-sized array of <TT>char</TT>.</p><p>References:K&R Sec. 1, Sec. 7<br></p><!-- aend --><p><hr><a href="delete.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="dospath.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/osdep/copy.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:59:02 GMT --></html>⌨️ 快捷键说明
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