@grt_sorted =
  map {substr $_ => $max_l}
  sort
  map {uc () . ("\0" x ($max_l - length)) . $_} @array;

##</code><code>##

map { my $c = uc () . ("\0" x ($max_l - length)) . $_;
      print "$_ => $c\n"; $c } @array;