Hi,
in addition: as long as you don't assign something (even undef) to an index, the array element does not exist.

#!/usr/bin/perl
use strict;
use warnings;
my @x = ();

$x[10] = 1;
@x[1..3] = (1,1);
$x[5] = undef;

for(my $y=0; $y!=@x; $y++)
{
        if(exists($x[$y]))
        {
                print "$y exists";
        }

        if(defined($x[$y]))
        {
                print "\t$y defined";
        }

        print "\n";
}

prints: 
1 exists        1 defined
2 exists        2 defined
3 exists

5 exists




10 exists       10 defined
[download]

Although the value is not defined (undef), it still exists.
Regards,
svenXY