Accessing hashes in main program from subroutine

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

I have a script that contains a subroutine that takes a file, does some analysis, reads the results into two separate hashes and then returns the hashes to the main program. Or so I thought. When I do this in the subroutine just before sending the hashes back to the main program, it prints out the contents correctly


for my $key (keys %$tData)
{
     my $value = $tData{$key};
     print "overlap: $key $value\n";

}
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I then send the hashes back to the program thus


 return($tData, $aData);
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The subroutine is called in the main program as follows:


my ($tOVERLAPData, $aOVERLAPData) = getOVERLAPData($fOVERLAP);
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And then try to print out the contents of the same hashes within the same program but it seems that the hashes aren't being returned as I'm not getting any print out of the content. Can anyone suggest why this might be so? I know i haven't given you much code but I'm assuming I've just done something rather silly as returning a hash should be a trivial process should it not? The hashes DO exist in the subroutine and i can print out the contents just fine - I just can't get to them in the main program.

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Re: Accessing hashes in main program from subroutine by mickeyn (Priest) on Jan 09, 2008 at 15:58 UTC
hi, seems like you have a bug in `$tData{$key}` this access `%tData` and NOT referenced hash `$tData`. try changing to `$tData->{$key}` and check again. BTW, `use strict` would have told you you're doing something wrong here ... HTH, Mickey	[reply] [d/l] [select]
Re^2: Accessing hashes in main program from subroutine by Angharad (Pilgrim) on Jan 09, 2008 at 16:23 UTC
thanks a lot. That worked a treat :)	[reply]
Re: Accessing hashes in main program from subroutine by toolic (Bishop) on Jan 09, 2008 at 15:59 UTC
I think you mean to say that `$tData` and `$aData` are references to hashes. Without seeing more of your code, you might try debugging using ref and Data::Dumper to make sure you have what you think you have. `use Data::Dumper; print Dumper(\$tdata);` [download]	[reply] [d/l] [select]