Hi All,
  I use nested data strcutures quite a lot, and can easily end up with arrays, inside hashes, inside arrays, etc. Now when I'm looping through I like to use foreach as it makes the notation shorter. For example:- 
my $ref;
$ref = [
          {
           "key1" => 'a',
           "key2" => 'b',
          },
          {
           "key1" => 'c',
           "key2" => 'd',
          },
        ];

foreach $hashref (@{$ref}) {
    print $hashref->{'key1'};
}#foreach

[download]
  Now I sometimes I want to know the array item number so I end up doing a for:- 
for (my $item = 0; $item <= $#{$ref}; $item++) {
    print $item;
    print $ref->[$item]->{'key1'};
}#for

[download]
As you can see the print is much longer, when the data structure is more complex this can be a really big difference.
Is there a good way of getting the benefits of the notation in the first example while knowing the array item number. Is it safe to:- 
my $item = 0;
foreach $hashref (@{$ref}) {
    print $hashref->{'key1'};
    $item++;
}#foreach

[download]
Most the time the data is loading from files and I do not know how the foreach loop with deal with missing array items, such as:- 
my $ref;
$ref->[0]->{'key1'} = "a";
$ref->[5]->{'key1'} = "b";
my $item = 0;
foreach $hashref (@{$ref}) {
    print $item;
    print $hashref->{'key1'};
    $item++;
}#foreach

[download]

Having written this, I realized I could answer my own questions simply by testing the final code example, perl does indeed fill in any missing array items producing the result I expected. I thought I'd post this anyway encase others have similar questions, or I'm sure there might be some interesting comments.

Lyle

In reply to looping through array references by cosmicperl

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