#!/usr/local/bin/perl
use strict;
my @dow=();   #array initialization is different from indexes initialization
$dow[0]=undef;
$dow[6]= "sat";

for(my $i=0; $i <=6;$i++){
        if(!(defined($dow[$i]) || exists($dow[$i]))){print "\$dow[$i] \t not defined\n";}
        if(exists($dow[$i]) && !defined($dow[$i])){ print "\$dow[$i]\texists\t not defined\n"; }
        if(exists($dow[$i]) && defined($dow[$i])){ print "\$dow[$i]\texists\t defined\n" ;}
        }