C:\Documents and Settings\my\Desktop>perl test.pl
0  ==== zero
1  ==== one
2  ==== three
3  ==== four
4  ==== four


##</code><code>##

#!/usr/bin/perl

use warnings;
use strict;

my %hash = (
            "0" => "zero",
            "1" => "one",
            "2" => "two",
            "3" => "three",
            "4" => "four"
            );

delete $hash{2};

my $num = "-1";

foreach (sort keys %hash) {
   $num++;
   my $value = $hash{$_};
   $hash{$num} = $value;
   }


foreach (sort keys %hash) {
   print "$_  ==== $hash{$_}\n";
   }