Sorting hash of hashes by values

[winnie_pooh]

#!/usr/bin/perl
use strict;
use warnings;

my %HoH = (
0 => {
    b  => 2,
    a  => 1, 
    e  => 5,
    c  => 3,
    d  => 4,
}
);

foreach my $key (sort { $HoH{0}{$a} cmp $HoH{0}{$b} } keys $HoH{0}) {
    my $value = $HoH{0}{$key};
    print $value->{$key}, "\n";
}

In the above hash of hashes (showed just entry for $HoH{0}), I'd like to sort the inside hash by values, so that I get output like this:

1 -> a
2 -> b
3 -> c
4 -> d
5 -> e

I know the loop is wrong... any help? Thanks a lot!

[tangent]

You're almost there, just change the print statement to:

print "$value -> $key\n";

If all of the values are numeric you should change the comparison operator to <=> like so:

foreach my $key (sort { $HoH{0}{$a} <=> $HoH{0}{$b} } keys %{$HoH{0}} 
+) {
    my $value = $HoH{0}{$key};
    print "$value -> $key\n";
}

[choroba]

The loop is fine. Replace the print line with

    print "$key => $value\n";

[AnomalousMonk]

foreach my $key (sort { ... } keys $HoH{0}) { ... }


Note that keys can be passed  $HoH{0} (assuming  @HoH as given in the OP), i.e., passed a hash reference, only with Perl version 5.14+.

[AnomalousMonk]

print $value->{$key}, "\n";


But why doesn't this print statement from the OPed code work?

Because in the  $value->{$key} expression, the  -> operator (see The Arrow Operator in perlop) expects the scalar  $value to be a reference to something, and the  {$key} part of the expression sez that that something is a hash (due to the  {} curly braces) for which the  $key scalar will be used as a key.

However, in the  @HoH hash as defined in the OP, all the values of the hash referenced by  $HoH{0} are humble numbers like 4 or 2 and possess no referential mojo.

[LanX]

The print is wrong.

update

needed time to start my laptop for a detailed answer, but you already got two good answers in the meantime... =)