Someone with the same problem? I have a 16 digit number starting with a 4 and my code identifies it correct as VISA\n, but the check50 says it has to be INVALID\n. What could cause this strange behaviour?
4111111111111113 isn't a valid card number because it doesn't come out correctly with the Luhn algorithm. It looks like you've got the part of the problem where you check the card's company, but it doesn't look like you have the part of the problem where you check if the card is valid with the Luhn algorithm.