#!/usr/bin/env perl
use strict;
use warnings;
my $x = 'abc';
if ($x =~ /b/) { print "y\n" } else { print "n\n" }
if ($x =~ 'b') { print "y\n" } else { print "n\n" }
if ($x =~ ?b?) { print "y\n" } else { print "n\n" }