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From: merlyn@iwarp.intel.com (Randal L. Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: Comparing numbers and regular expressions
Message-ID: <1991Feb2.014512.23396@iwarp.intel.com>
Date: 2 Feb 91 01:45:12 GMT
References: <5152@s3.ireq.hydro.qc.ca>
Sender: news@iwarp.intel.com
Reply-To: merlyn@iwarp.intel.com (Randal L. Schwartz)
Organization: Stonehenge; netaccess via Intel, Beaverton, Oregon, USA
Lines: 81
In-Reply-To: gamin@ireq-robot.hydro.qc.ca (Martin Boyer)

In article <5152@s3.ireq.hydro.qc.ca>, gamin@ireq-robot (Martin Boyer) writes:
| $uid_list = "13|1";
| 
| $this_uid = 101;
| 
| if ($this_uid =~ /^$uid_list$/o) {
|     print "Matches!\n";
| } else {
|     print "Doesn't match.\n";
| }
| 
| This section prints Matches!, but that's not what I want; what I want
| is for the test to succeed only for values of 13 or 1.
| 
| Can anybody enlighten me?

Yeah.  (I hope.)  Look at the regular expression you are building:

	/^13|1$/

This matches anything that starts with a 13, or anything that ends in
a 1, of which 101 is clearly an example.  What you want instead is:

	/^(13|1)$/

And, backtracking that into your code:

##################################################
$uid_list = "13|1";

$this_uid = 101;

if ($this_uid =~ /^($uid_list)$/o) {
    print "Matches!\n";
} else {
    print "Doesn't match.\n";
}
##################################################

On which I get "Doesn't match.".

I wouldn't do it that way, actually.  I'd opt first for an assoc
array, as in:

##################################################
for (13,1) {
	$cool{$_}++;
}

if ($cool{101}) {
	print "Yes!\n";
} else {
	print "No!\n";
}
##################################################

If the values of array are well behaved, I could go for a bitmap,
like:

##################################################
$cool = "";

for (13,1) {
	vec($cool,$_,1) = 1;
}

if (vec($cool,101,1)) {
	print "Yes!\n";
} else {
	print "No!\n";
}
##################################################

There's More Than One Way To Do It, sez Larry.

print pack("h*",unpack("H*","\244W7G\002\026\346\366G\206V'\002\005V'\306\002\206\0266\266V'\302"))
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
| on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III      |
| merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn |
\=Cute Quote: "Intel: putting the 'backward' in 'backward compatible'..."====/