#!usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my %hash;
my $i;

fill_hash(\%hash);      # add some data
print Dumper \%hash;    # dump it
fill_hash(\%hash);      # add more data
print Dumper \%hash;    # dump it again
exit;

sub fill_hash {
    my $hash_ref = shift || {};
    $hash_ref->{$i} = ord(++$i) for 1..4;
}