From David Shaw's recipe
def cardLuhnChecksumIsValid(card_number): sum = 0 num_digits = len(card_number) oddeven = num_digits & 1 for count in range(0, num_digits): digit = int(card_number[count]) if not (( count & 1 ) ^ oddeven ): digit = digit * 2 if digit > 9: digit = digit - 9 sum = sum + digit return ( (sum % 10) == 0 )
