my $str = "Hello";
print reverse $str;

##</code><code>##

sub rev_scalar {
  my $data = shift;
  my $i;
  my $tmp;

  for($i = 0; $i < int(length($$data)/2); $i++) {
    $tmp = substr($$data,$i,1);
    substr($$data,$i,1) = substr($$data,-($i+1),1);
    substr($$data,-($i+1),1) = $tmp;
  }
}