#!/usr/bin/perl

use strict;

my %Hash;

$Hash{a}[0]="i";
$Hash{a}[1]="ii";
$Hash{a}[2]="iii";
$Hash{b}[0]="iv";
$Hash{b}[1]="v";
$Hash{b}[2]="vi";

foreach my $var (sort keys %Hash) {
   print "$var,";
   foreach my $val (@{$Hash{$var}}) {
       if (defined $val) {
         print "$val,";
      }
   }
}

exit;

__END__