void local fn StringHasUniqueCharacters( string as CFStringRef )
  long i, j, length = len( string )

  if length == 0 then printf @"The string \"\" is empty and thus has no characters to compare.\n" : exit fn

  printf @"The string: \"%@\" has %ld characters.", string, length

  for i = 0 to length - 1
    for j = i + 1 to length - 1
      if ( fn StringIsEqual( mid( string, i, 1 ), mid( string, j, 1 ) ) )
        CFStringRef duplicate = mid( string, i, 1 )
        printf @"The first duplicate character, \"%@\", is found at positions %ld and %ld.", duplicate, i, j
        printf @"The hex value of \"%@\" is: 0X%x\n", duplicate, fn StringCharacterAtIndex( duplicate, 0 )
        exit fn
      end if
    next
  next
  printf @"All characters in string are unique.\n"
end fn

fn StringHasUniqueCharacters( @"" )
fn StringHasUniqueCharacters( @"." )
fn StringHasUniqueCharacters( @"abcABC" )
fn StringHasUniqueCharacters( @"XYZ ZYX" )
fn StringHasUniqueCharacters( @"1234567890ABCDEFGHIJKLMN0PQRSTUVWXYZ" )

HandleEvents