Re: hashes with multiple values per key

use strict;
use warnings;

my %yahoo = ();

while (<DATA>) {
    chomp;
    my ($value, $key) = split;
    $yahoo{$key} += $value;
}

foreach my $key (sort keys %yahoo) {
       print "$key: $yahoo{$key}\n";
}
__DATA__
12 AAAA
12 AAAA
15 BBBB
1222 CCCC
1 BBBB
[download]

Output:

AAAA: 24
BBBB: 16
CCCC: 1222
[download]

Comment on Re: hashes with multiple values per key Select or Download Code

Replies are listed 'Best First'.
Re^2: hashes with multiple values per key by convenientstore (Pilgrim) on Aug 07, 2007 at 00:30 UTC
I didn't think below would work but it works `$yahoo{$key} += $value;` [download] isn't above same as `$yahoo{$key} = $yahoo{$key} + $value` [download] so first $yahoo{$key} would be null + $value and then next time it would come up with that value so that's why it works great!! thank you. Grandfather's solution , is bit advance for me, as I have not got to module part but I am reading that tonight and will try. thank you both !!!	[reply] [d/l] [select]
Re^3: hashes with multiple values per key by kyle (Abbot) on Aug 07, 2007 at 00:41 UTC
Yes, "`$yahoo{$key} += $value;`" is the same as "`$yahoo{$key} = $yahoo{$key} + $value;`". Look under "Assignment operators" in perlop.	[reply] [d/l] [select]
Re^4: hashes with multiple values per key by GrandFather (Saint) on Aug 07, 2007 at 01:10 UTC
not quite. Consider: `use strict; use warnings; my $foo = undef; my $bar = undef; $foo += 1; $bar = $bar + 1;` [download] Generates the warning: `Use of uninitialized value in addition (+) at noname1.pl line 8.` [download] Note that it is the $bar line only that generates the warning. The update assignment operators do not generate an uninitialized value warning when the left hand side is undefined, but the other non-boolean binary operators do. See perlsyn Declarations. DWIM is Perl's answer to Gödel	[reply] [d/l] [select]