use strict;
use warnings;

my $undef;
my $non_numeric_str = 'abc';

print "it's 0\n" if $undef           == 0;
print "it's 0\n" if $non_numeric_str == 0;

##</code><code>##

Use of uninitialized value in numeric eq (==) at script.pl line 7.
it's 0
Argument "abc" isn't numeric in numeric eq (==) at script.pl line 8.
it's 0