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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!-- but may not be published or retransmitted without explicit permission.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 lib1.sgml dated Sat Feb 7 18:46:53 2004 --><!-- corresponding to FAQ list version 4.0 --><html><!-- Mirrored from c-faq.com/lib/regex.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:59 GMT --><head><meta name=GENERATOR content="faqproc"><title>Question 13.7</title><link href="strtok.html" rev=precedes><link href="qsort1.html" rel=precedes><link href="index.html" rev=subdocument></head><body bgcolor="#ffffff"><a href="strtok.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="qsort1.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 13.7</h1><p><font face=Helvetica size=8 color=blue><b>Q:</b></font>I need some code to doregular expressionandwildcard matching.</p><p><hr><p><font face=Helvetica size=8 color=blue><b>A:</b></font>Make sure yourecognizethedifference between:</p><UL><li>Classicregular expressions,variants of which are used in such Unix utilities as<TT>ed</TT> and <TT>grep</TT>.In regular expressions,a dot <TT>.</TT> usually matches any single character,and the sequence <TT>.*</TT> usually matches any string of characters.(Of course,full-blownregular expressions have several more featuresthanthese two.)<li>Filenamewildcards,variants of which are used by most operating systems.There is considerably more variationhere(in particular,MS-DOS wildcards aresomewhat stunted),but it is often the case that<TT>?</TT> matches any single character,and <TT>*</TT> matches any string of characters.</UL><p>There are a number of packages available for matching regular expressions.Most packages use a pair of functions,one for ``compiling'' the regular expression,and one for ``executing'' it(i.e. matching strings against it).Look for header files named <TT><regex.h></TT>or <TT><regexp.h></TT>,and functions called<TT>regcmp</TT>/<TT>regex</TT>,<TT>regcomp</TT>/<TT>regexec</TT>,or<TT>re_comp</TT>/<TT>re_exec</TT>.(These functions mayexistin a separate regexp library.)A popular,freely-redistributableregexp packageby Henry Spencer is available fromftp.cs.toronto.edu in pub/regexp.shar.Zor in several other archives.The GNU project has apackagecalled rx.<a href="offload.html" rel=subdocument>[footnote]</a>See also question <a href="../resources/sources.html">18.16</a>.</p><p>Filename wildcard matching(sometimes called``globbing'')isdonein a variety of ways ondifferentsystems.On Unix,wildcards are automatically expanded by the shellbefore a process is invoked,so programs rarely have to worry about them explicitly.Under MS-DOS compilers,there is often a special object filewhich can be linked into a programtoexpand wildcardswhile <TT>argv</TT> is being built.Several systems(including MS-DOS and VMS)providesystem services forlisting or opening files specified by wildcards.Check your compiler/library documentation.See also questions<a href="../osdep/readdir.html">19.20</a>and<a href="../misc/argv.html">20.3</a>.</p><p>Here is a quick little wildcard matcher by Arjan Kenter:<pre>int match(char *pat, char *str){ switch(*pat) { case '\0': return !*str; case '*': return match(pat+1, str) || *str && match(pat, str+1); case '?': return *str && match(pat+1, str+1); default: return *pat == *str && match(pat+1, str+1); }}</pre>(Copyright1995,Arjan Kenter)</p><p>With this definition,the call <TT>match("a*b.c", "aplomb.c")</TT>would return 1.</p><p>References:Schumacher, ed., <I>Software Solutions in C</I> Sec. 3 pp. 35-71<br></p><!-- aend --><p><hr><a href="strtok.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="qsort1.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/lib/regex.html by HTTrack Website Copier/3.x [XR&CO'2008], Sat, 14 Mar 2009 07:58:59 GMT --></html>⌨️ 快捷键说明
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