Re: duplicate keys on hash

you're supposed to use hash references into arrays?

The data structure you're probably looking for is a hash, where each value is a reference to an individual array - a "hash of arrays". The links that Happy-the-monk provided above should explain.

But I don't see how(in example) typing in the "2" would pull up both BBB AND EEE

"Access and Printing of a HASH OF ARRAYS" in perldsc shows you some examples of how to access the data structure. It'd probably also be helpful to you if you learn about how to handle references in general, e.g. perlreftut.

To get you started, here's one way to build such a structure from the input you showed. One important concept here is autovivification, which is what causes you to be able to write @{$data{$k}} and have a reference to a new array spring into existence ("vivify") even if $data{$k} was previously undefined.

use warnings;
use strict;
my %data;
while (<DATA>) {
    chomp;
    next unless /\S/;
    my ($k,$v) = /^\s*(\S+)\s+(.+?)\s*$/;
    push @{$data{$k}}, $v;
}
use Data::Dumper;
print Dumper(\%data);
__DATA__
1 AAA 
2 BBB
3 CCC
4 DDD
2 EEE
[download]

Output:

$VAR1 = {
          '3' => [
                   'CCC'
                 ],
          '1' => [
                   'AAA'
                 ],
          '4' => [
                   'DDD'
                 ],
          '2' => [
                   'BBB',
                   'EEE'
                 ]
        };
[download]

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Re^2: duplicate keys on hash by Happy-the-monk (Canon) on Feb 11, 2015 at 13:21 UTC
While replying to above Anonymonk I am actually clarifying to OP But I don't see how(in example) typing in the "2" would pull up both BBB AND EEE The possibly missing information is the syntax used above to treat the hash value - spelled out `$hash{$key}` - as if it were a plain array is to put it inside this thingy `@{ ... }` instead of the dots. You have been shown that it gets into the hash value with the simple push function. Getting stuff out works the same way: `foreach my $key ( keys %hash ) { foreach my $value ( @{ $hash{$key} } ) { print $key, ": ",$value, "\n" # or whatever you want to do. } }` [download] Cheers, Sören Créateur des bugs mobiles - let loose once, run everywhere. (hooked on the Perl Programming language)	[reply] [d/l] [select]

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Re^2: duplicate keys on hash
by Happy-the-monk (Canon) on Feb 11, 2015 at 13:21 UTC

While replying to above Anonymonk I am actually clarifying to OP

But I don't see how(in example) typing in the "2" would pull up both BBB AND EEE

The possibly missing information is the syntax used above to treat the hash value - spelled out $hash{$key} - as if it were a plain array is to put it inside this thingy @{ ... } instead of the dots.

You have been shown that it gets into the hash value with the simple push function.

Getting stuff out works the same way:

foreach my $key ( keys %hash )
{
    foreach my $value ( @{ $hash{$key} } )
    {
        print $key, ": ",$value, "\n" # or whatever you want to do.
    }
}
[download]

Cheers, Sören

Créateur des bugs mobiles - let loose once, run everywhere.
(hooked on the Perl Programming language)

[reply]
[d/l]
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