my $j = 0;

for (my $i = 0; $i <= $#array; ++$i) {
  $current = $array[$i];
  if($current == undef) {
    push @empty, $j++;
  }
}

print "undefined indices:  @empty \n";

[download]
or to put it in common perl terms 
my @empties = ();
for my $i(0..$#array) {
   unless(defined $array[$i]) {
       push @empties, $i;
   }
}
print "undefined indices @empties\n";

[download]

{Editor's note: This example doesn't work as the poster thought it would. See Abigail-II's explanation here: Re: Answer: How do I test if an array is empty or not?.}

Edited by davido for clarification.

In reply to Re: How do I test if an array is empty or not? by rajib
in thread How do I test if an array is empty or not? by Anonymous Monk

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