This Ruby file includes Ruby functions that Luhn algorithm is implemented. Function ,"checkLuhn1 check if current barcode(included check digit) validates. Function, "checkLuhn2" returns value that current barcode join with its checkdigit as suffix. /********************************************/ [note] Here, I have used Bitwise Operator instead o…

calcChecksum.rb

def sumLuhn (barcode, nParity)
  checksum = 0
	for i in 0..barcode.length - 1
		nDigit = barcode[i].to_i
		if nParity == ( i & 1 ) # i % 2
			nDigit = ( nDigit << 1 ) # nDigit * 2
		end
		checksum = checksum + nDigit / 10 + nDigit % 10
	end
	return checksum % 10
end

#return turn if current barcode( including checkdigit ) validates, false if not.

def checkLuhn1(barcode)
	nParity = ( barcode.length & 1 ) # barcode.length % 2 
	return sumLuhn(barcode, nParity) == 0
end

#return string if current barcode joined checkdigit as suffix.

def checkLuhn2(barcode)
	nParity = ( 1 ^ ( barcode.length & 1 ) ) # 1 - ( barcode.length % 2 )
	checksum = sumLuhn(barcode, nParity)
	return barcode + "#{ ( 10 - checksum % 10 ) % 10 }"
end

puts checkLuhn1( "79927398713" ) # return ture if valid barcode, return false if invalid barcode
puts checkLuhn2( "7992739871" ) # return checkcode