class CreditCardDetector::Luhn

Class to validate Luhn numbers.

Public Class Methods

valid?(number) click to toggle source
# File lib/credit_card_detector/luhn.rb, line 4
def self.valid?(number)
  s1 = s2 = 0

  number.to_s.reverse.chars.each_slice(2) do |odd, even|
    s1 += odd.to_i

    double = even.to_i * 2
    double -= 9 if double >= 10
    s2 += double
  end

  (s1 + s2) % 10 == 0
end