c:\@Work\Perl\monks>perl -le "use strict; use warnings; ;; use Data::Dump qw(dd); ;; my ($value, $alice, $bob); ;; $value = $alice eq $bob; dd 'result of comparison of undefined values', $value; " Use of uninitialized value in string eq at -e line 1. Use of uninitialized value in string eq at -e line 1. ("result of comparison of undefined values", 1)