Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Parens in a reg exp
Message-ID: <9488@jpl-devvax.JPL.NASA.GOV>
Date: 13 Sep 90 01:37:52 GMT
References: <MIKE.MCMANUS.90Sep12091652@mustang.FtCollins.NCR.com>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Distribution: comp
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 55

In article <MIKE.MCMANUS.90Sep12091652@mustang.FtCollins.NCR.com> Mike.McManus@FtCollins.NCR.com (Mike McManus) writes:
: 
: I'm reading tokens in from a file and doing compares on the token, sort of
: like:
: 
: @toklist = ("VDD", "GND", IN", "OUT", "INOUT");
: 
: while(<>) {
:     if( do IS_TERM()) {
:     ...
:     }
: }
: 
: sub IS_TERM() {
:     $token = (split)[1];
:     if( join( " ", @tklist) !~ /$token/) {return(0);}
:     foreach $i (@toklist) {
:         if( $i eq $token) {
:             .... 
:             return(1);
:         }
:     }
:     return(0);
: }
: 
: # Warning!  Not the REAL perl code, but a resonable facsimile thereof...
: 
: The problem I run into is when $token is something containg a meta character.
: Specifically, things die when $token = "IF(".  Anybody got any ideas about a
: work around?  I tried some things, but am a green enuff novice that I didn't
: have much luck.
: 
: NOTE:  I use the 'if(join...) return 0' as a quick and dirty check, before
: launching into a 'foreach $i (@toklist)', so as to save time.  Will it, can
: forget about it.  This would solve my problem, too.

To solve your immediate problem, quote metacharacters by saying

	$token =~ s/(\W)/\\$1/g;

However, any time you're doing a linear search in Perl, you're probably
doing it wrong.  Learn to think in terms of associative arrays.

What you want is something like this:

%isterm = ("VDD", 1, "GND", 1, IN", 1, "OUT", 1, "INOUT", 1);

while(<>) {
    ($junk, $token) = split;
    if( $isterm{$token} ) {
    ...
    }
}

Larry