#!/usr/bin/env perl -l

use strict;
use warnings;

my $string = 'abc|def';

if ($string =~ /(\S{3})\|(\S{3})/) {
    print "After first match (in if condition): \$1=$1 \$2=$2";
    my $whatever = 'blah';
    $whatever =~ s/b/c/;
    print "After second match (in substitution): \$1=$1 \$2=$2";
}

##</code><code>##

After first match (in if condition): $1=abc $2=def
Use of uninitialized value $1 in concatenation (.) or string at ./pm_1143443_match_vars.pl line 12.
Use of uninitialized value $2 in concatenation (.) or string at ./pm_1143443_match_vars.pl line 12.
After second match (in substitution): $1= $2=