#!/usr/local/bin/perl  
use strict;
use Tie::IxHash;
my %foo;
my $t = tie %foo, 'Tie::IxHash';

#integer part of...
%foo = qw (    one 1.2
               one 1.6
	         one 1.9
	         two 2
	         three 3 );

my @keys = $t->Keys;
 print "@keys\n";