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Re^5: Array to hash converstion

by dsheroh (Prior)
on Jul 15, 2009 at 09:41 UTC ( #780228=note: print w/replies, xml ) Need Help??


in reply to Re^4: Array to hash converstion
in thread Array to hash converstion

The issue you've run into here is that each hash key can only be associated with a single value, so the second assignment to $hash{one} overwrites its previous value. Or, as spazm put it in the comment you were replying to,
My solutions below assume that you have unique key values, or are un-interested in collisions. In the case of a collision, the last reference to the key wins.
However, the single value held by the hash doesn't have to be a simple scalar. If you use an array reference there (giving you a "hash of arrays" or "HoA"), then the code will be a little more complex, but you'll be able to store as many values as you like with each key:
#!/usr/bin/perl use strict; use warnings; my @value_pairs = qw( one abc two xyz one def ); my %hash; while (@value_pairs) { my $key = shift @value_pairs; my $value = shift @value_pairs; push @{$hash{$key}}, $value; } for my $key (keys %hash) { print "key $key has values: ", join(', ', @{$hash{$key}}), "\n"; } __END__ key one has values: abc, def key two has values: xyz

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Re^6: Array to hash converstion
by gem555 (Acolyte) on Jul 15, 2009 at 10:25 UTC
    $correction = $data_pair->{value} if($data_pair->{key} eq 'correct');
    how to store the value in $correction only if the $data_pair->{value} is not empty.
      check to see if it is empty (whatever that means :D)
      $correction = $data_pair->{value} if exists $data_pair->{value} and # could be undef defined $data_pair->{value} and # at least "" length $data_pair->{value} and # has length $data_pair->{value} and # has true value $data_pair->{key} eq 'correct';

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