use strict;
use warnings;
my $abc = "AABCBAABCCCCAB";
my $ab  = "AABABAABABABAB";
$abc =~ s/[^ab]/./gi;
print "They match!\n" if $ab =~ /^$abc$/i;

##</code><code>##

print "They match!\n" unless ($abc ^ $ab) =~ /\x{3}/;