in reply to Accessing hash elements inside another hash

Hard to answer that question. Your printing code iterates over %Data. You are populating %Queues. But you aren't putting hash(refs) as values of %Queues, but arrayrefs, which contain hashes. So you have hashes containing arrays containing hashes.

And your printing code assumes the keys of %Data are hashes. The never ever are. Hash keys are always strings. No exceptions. (Strings can be used as hashes if you want to use symbolic references. But I advice you not to. And if you want to anyway, you're are on your own).

  • Comment on Re: Accessing hash elements inside another hash

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Re^2: Accessing hash elements inside another hash
by bar10der (Beadle) on Mar 11, 2009 at 15:05 UTC
    Sorry, made a mistake in putting code. Actually %queues is prepared and returned by a sub routine into %Data. So the code is - 
    my %Data = getQueues();

while (my ($key,$value) = each(%Data)){
    #print "$key = $value \n";
    for(my ($k,$v) = each($key->{'Queues'})){
        print "$k = $v \n";
    }
}

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[d/l]
      You're use of $key in the inner loop is incorrect. It should be: 
      my %Data = getQueues();

while (my ($key,$value) = each(%Data)){
    #print "$key = $value \n";
    for(my ($k,$v) = each($Data{$key}->{'Queues'})){
        print "$k = $v \n";
    }
}

      [download]
      In general, accessing all key/value pairs in a HoH will look like: 
      foreach my $key (keys(%HoH)){
  foreach my $otherKey (keys($HoH{$key})){
    my $value = $HoH{$key}{$otherKey};    
    my $result = &DO_SOMETHING($value);
  }
}

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        You're use of $key in the inner loop is incorrect.

        Yours is too... a hash reference cannot be stored (directly) as a hash key, only as value. so that should look like 

        my %Data = getQueues();

while (my ($key,$value) = each(%Data)){
    #print "$key = $value \n";
    for(my ($k,$v) = each(%$value)){
        print "$k = $v \n";
    }
}

        [download]

        although that snippet doesn't fit the OP's data structure, either. The following might work: 

        while (my ($key,$value) = each(%Data)){
    if (ref $value eq 'ARRAY') {
        for my $hashref (@$value) {
            print "  $_ => $hashref->{$_}\n" for keys %$hashref;
        }
    } else {
    print "$key = $value \n";
}

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