thegeekexplorer / gtin-validation Goto Github PK

Hi There, what license is this code under? It would be helpful for code re-use if you selected a license such as MIT.

Hi,

There are 2 issues with the validation in the Swift version of the algorithm.

First:

• there are GTINs with also 17 and 18 digits. Currently you only check for 8, 12, 13 and 14.

Second:

• The calculation of the checkSumDigit like (let checkSumDigit = 10 - checkSum % 10) is wrong when you have checkSum 0.
  You can simply divide the result to %10, if you want to work with the reminder like:
  let checkSumDigit = (10 - checkSum % 10) % 10

or do something more complex, but exactly what you write in the comment by finding the first bigger number and subtracting from it like:
let nextMultipleOf10 = Int(ceil(Float(checkSum) / 10)) * 10
let checkSumDigit = nextMultipleOf10 - checkSum

You can check this with GTIN with checkSum 0 like: 7630872279104

Best regards,
Archangel