This morning I came across this problem, see the below code. For a while, I obviously had the wrong impression, thought hash keys would keep its own "type". Now I realized that Perl actually stringify the hash keys, so when I do a sort keys, it actually gave me the alphabetical order, not the numeric order I was expecting.

I am thinking whether it is more reasonable, to make the native order as the default order, unless:
  1. there is no native order for that type (for example, I have an OO class called Book, it world be nice if I have a way to define the native order for this class as sort by ISDN number, which is an attribute of the Book class), or
  2. keys are in different types (for example, some are numbers, some are strings)
then use the stringified order.

use Data::Dumper;
use strict;

my $hash = {};
for (1..100) {#keys are all numbers, from the users' point of view
        $hash->{$_} = "a";
}

my @keys = keys %$hash;#this is the internal order, I don't care
print(join(",", @keys));
print "\n", "=" x 70, "\n";

my @sorted = sort @keys;#this will sort as strings!!
print(join(",", @sorted));
print "\n", "=" x 70, "\n";

my @sorted_as_num = sort {$a <=> $b} @keys;#force it to sort as number
print(join(",", @sorted_as_num));
print "\n", "=" x 70, "\n";

print Dumper($hash);

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In reply to sort hash keys as numbers and maybe even more... by pg

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