return multiple hashes from a sub

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

Hi Monks,

Can anyone tell me if it's possible/and how to return multiple hashes from a sub routine?
Something like below (this isnt working):

#!/usr/bin/perl

use strict;

my (%hash1, %hash2) = &build_hashes;

foreach (keys (%hash1)) {
  print $_, ":", $hash1{$_}, "\n";
} # end-foreach

foreach (keys (%hash2)) {
  print $_, ":", $hash2{$_}, "\n";
} # end-foreach


sub build_hashes {
  my %hash1 = { 1=>"foo1", 2=>"bar1" };
  my %hash2 = { 3=>"foo2", 4=>"bar2" };
  return (\%hash1, \%hash2);
} # end-sub
exit;
[download]

Cheers,
Reagen

Comment on return multiple hashes from a sub Download Code

Replies are listed 'Best First'.
Re: return multiple hashes from a sub by monkey_boy (Priest) on Feb 03, 2005 at 14:28 UTC
You need to read about references, but heres the answer ... `my ($hash1, $hash2) = &build_hashes; foreach (keys (%{$hash1})) { print $_, ":", $hash1->{$_}, "\n"; } # end-foreach foreach (keys (%{$hash2})) { print $_, ":", $hash2->{$_}, "\n"; } # end-foreach sub build_hashes { my %hash1 = ( 1=>"foo1", 2=>"bar1" ); my %hash2 = ( 3=>"foo2", 4=>"bar2" ); return (\%hash1, \%hash2); } # end-sub exit;` [download] Im so sick of my Signature...	[reply] [d/l]
Re: return multiple hashes from a sub by pelagic (Priest) on Feb 03, 2005 at 14:31 UTC
Your initialising was wrong; use: `my %hash1 = ( 1=>"foo1", 2=>"bar1" ); ## instead if my %hash1 = { 1=>"foo1", 2=>"bar1" };` [download] ... no curlies! pelagic	[reply] [d/l]
Re: return multiple hashes from a sub by chb (Deacon) on Feb 03, 2005 at 14:32 UTC
Try dereferencing the hash references you get from your sub: `foreach (keys %$hash1) { ... }`.	[reply] [d/l]
Re: return multiple hashes from a sub by aquarium (Curate) on Feb 03, 2005 at 14:24 UTC
The modular approach calls for a build_hash sub, which gets called with parameters (twice) to build each hash, and return a reference to that. if you programmed this in OO style, it would be similar to the modular -- divide and conquer -- approach. The other way is to return a reference to an anonymous hash/array of hashes. just a little different to dereference then. the hardest line to type correctly is: stty erase ^H	[reply]