#!/usr/bin/perl
my (@ar1, @ar2);

$ar1[0] = 1;
$ar1[1] = 0; # a defined element, not NULL
$ar1[7] = 9; # skip, leaving 2..6 undefined

# dump array 1
print("\@ar1:\n");
for my $i (0..$#ar1) {
   print("   $i : $ar1[$i]\n");
}

# weed the undefined elements
@ar2 = grep { defined $_ } @ar1;

print("\@ar2:\n");
for my $i (0..$#ar2) {
   print("   $i : $ar2[$i]\n");
}