Whats happening to my hash ref.

Scarborough has asked for the wisdom of the Perl Monks concerning the following question:

I have a sub get_vars_hash which returns a a reference to a hash.

 
#%vars has the structure $vars{$name} = [$local, $value]
return \%vars
[download]

Back in main I have the following code

my $vars = get_vars_hash($file);

Dumper(\%$vars);  #just for testing.
#outputs
#$var1 = {
#         'DATE'=>[
#                  'G234_DATE',
#                  'ZERO'
#                 ],
#         'STOP'=>[
#                  'G234_STOP''
#                  '60'
#                 ]
#         }
#Which is what I expected

foreach $key (keys(%$vars)){
    print "$key\n";
}
#outputs
#DATE
#ARRAY(0x1df50b0)
#STOP
#ARRAY(0x1df5074)
[download]

Not what I expected. Am I dereferencing the hash incorrectly? One last note the code and sub are called from a button press in a Tk GUI if that has any relevents.
Update:Maybe I've not been clear, I didn't expect to see the array refs at all, in the second bit of code as don't think they are keys in the hash. Maybe I'd better go back to a look at hashes again?

Comment on Whats happening to my hash ref. Select or Download Code

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Re: Whats happening to my hash ref. by tinita (Parson) on Jun 01, 2004 at 12:03 UTC
if Dumper outputs what you state above, and the loop over keys %$var outputs the array refs, then either your perl is broken or you're not posting your complete code. it's always recommendable to post a full code example with its output copied and pasted and not retyped. i think you retyped because you say this is the output from Dumper: `# 'STOP'=>[ # 'G234_STOP'' # '60' # ]` [download] can't be, there's two apostrophes and a missing comma. here's my complete example: Read more... (502 Bytes)	[reply] [d/l] [select]
Re: Re: Whats happening to my hash ref. by Scarborough (Hermit) on Jun 01, 2004 at 14:21 UTC
Thankyou Tinita, Your answer prompted me to look further then the end of my nose and look at my own work a little more objectively and found the problem lay entirely with me. I have fixed the problem and all is well now. Thanks for your help a very grateful Monk.	[reply]
Re: Whats happening to my hash ref. by BUU (Prior) on Jun 01, 2004 at 11:01 UTC
You're dereferencing the hash reference perfectly. It's the Array references that the hash contains that you aren't dereferencing. As Data::Dumper itself tells you by the use of `[]` around the elements.	[reply] [d/l]
Re: Whats happening to my hash ref. by Aragorn (Curate) on Jun 01, 2004 at 11:22 UTC
You get what you ask for, i.e. the array reference, which you have to dereference properly to get the elements of the array: `foreach $key (keys(%$vars)){ print "$key\n"; foreach $array_elem ({@$vars->{$key}}) { print "\t$array_elem\n"; } # You can also use something like this to get at the array # elements individually: # print $vars->{$key}->[0]; # first element }` [download] Arjen	[reply] [d/l]
Re: Whats happening to my hash ref. by El Linko (Beadle) on Jun 01, 2004 at 11:28 UTC
`Dumper( $vars );` [download] There is no need to dereference the hash and then rereference it in the call to Dumper. Apart from that it looks ok. If this is a cut'n'paste of the real code then adding use warnings and use strict may show something up. If not then maybe adding in the exact code causing the problem will help.	[reply] [d/l]