Question

This is probably an easy question but I can’t figure it out. I have a structure that is returned from a routine that, when I print with Data::Dumper, looks like

$VAR1 = {
  'date' => 'May 15, 2012',
  'value' => '0.20'
};

But I can’t get the data out of it. If I try $data{value} I get nothing. I am not that familiar with Perl. Can anyone help me? What am I missing?

Answer 1

Your $VAR1 is a hash ref, not just a hash. So you need to dereference the variable to get at the data:

$VAR1->{date}
$VAR1->{value}

This is Perl, so TMTOWTDI (There’s More Than One Way To Do It):

$$VAR1{date}
$$VAR1{value}

However, the explicit -> arrow operator is generally easier to understand; the operand on the left is a reference, and the bit on the right accesses it ($hash->[0] for an array ref; $hash->{item} for a hash ref).

You could use instead:

my %VAR2 = ('date' => 'May 15, 2012', 'value' => '0.20');

Now you can write:

$VAR2{date}
$VAR2{value}

(I could have used both %VAR1 and $VAR1; they’re distinct variables — but that’s extra confusing.)