This is what that structure (minimally) looks like:

%REFERRERS = (
  $campaign_id => {
    $skin_id => {
      $refr_url => __some_value__
    },
  },
);

[download]

...where $campaign_id, $skin_id, and $refr_url are scalar variables that hold the names of hash keys. There really is no $REFERRERS variable (a scalar), there is a %REFERRERS, which is a hash.

Perl has autovivification, so let's say that there doesn't yet exist a hash key named "foo". Then saying $REFERRERS{foo} = 1 causes that hash element to become available, and the value that hash element holds is 1. Let's say that your hash is entirely empty: %REFERRERS = () ...empty. By incrementing $REFERRERS{foo}{bar}{baz}++, an element inside of %REFERRERS is created, named 'foo'. Its value is set to a reference to an anonymous hash with a key named "bar", which is set to a reference to an anonymous hash with a key named "baz", and finally that element is incremented from its undefined state to "1".


Dave

In reply to Re: Initializing Hash Arrays in Perl by davido
in thread Initializing Hash Arrays in Perl by winterwind

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