in reply to Re: mildly tricky hash question
in thread mildly tricky hash question

That would give him a hash of arrays - not what he's looking for. You could join all the arrays right after your loop, or you could change it to 
my %reverse_hash;
foreach my $key ( keys %hash ) {
    $reverse_hash{$key}=$reverse_hash{$key}
                        ? "$reverse_hash{$key},$hash{$key}"
                        : $hash{$key};
}

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Re: Re: Re: mildly tricky hash question
by Anonymous Monk on Mar 30, 2004 at 19:33 UTC
    I'm getting an "undefined" error at the print statement when I use that bit of code. Warnings says that line 16 is using an uninitilized value..... what have I done wrong? 
    #!/usr/bin/perl -w
use strict;

my $key;
my %hash = (
             ball1 => 'red',
             ball2 => 'blue',
             ball3 => 'red',
           );
# thanks to http://www.perlmonks.org/index.pl?node_id=340896 for this 
+block of code

my %reverse_hash;
foreach $key ( keys %hash ) {
    $reverse_hash{$key} = $reverse_hash{$key}
                        ? "$reverse_hash{$key},$hash{$key}"
                        : $hash{$key};
}
print "$reverse_hash{red}\n";

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