Re: How do I test if an array is empty or not?

my $j = 0;

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

print "undefined indices:  @empty \n";
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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";
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{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.

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Re: Answer: How do I test if an array is empty or not? by Abigail-II (Bishop) on Aug 21, 2002 at 11:09 UTC
What your code is trying to do is extracting the undefined values (or rather, the indices) from the array - which is a different question. However, your first code fragment not only finds the indices with undefined values, but anything that is `0` in numeric context, which includes `0`, the empty string and the undefined value. Your second code fragment is correct, but it can be written in a more Perlesque way: `my @empties = grep {!defined $array [$i]} 0 .. $#array;` [download] As for the question, just use the array in scalar context. It's empty if the array is 0 in scalar context. Abigail	[reply] [d/l]

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Re: Answer: How do I test if an array is empty or not?
by Abigail-II (Bishop) on Aug 21, 2002 at 11:09 UTC

0

Your second code fragment is correct, but it can be written in a more Perlesque way:

    my @empties = grep {!defined $array [$i]} 0 .. $#array;
[download]

As for the question, just use the array in scalar context. It's empty if the array is 0 in scalar context.

Abigail

[reply]
[d/l]