sub zeroPad () {

  my $number     = $_[0];
  my $charLength = $_[1];

  if ($charLength > 10000) { return; }  # Sanity Check

  my $tmp;

  # Front pad with zeros
  $tmp = $number;
  while ( length ($tmp) < $charLength ) {
       $tmp = "0" . $tmp;
  }
  return $tmp;

} # end zeroPad