###
### binary3
###

## Chapter 5 section 4.2

sub binary {
  my ($n, $RETVAL) = @_;
  $RETVAL = "";
  while (1) {
    my $b = $n % 2;
    $RETVAL = "$b$RETVAL";
    return $RETVAL if $n == 0 || $n == 1;
    $n = int($n/2);
  }
}