Validate Credit card number

[Praveens]

Hi, I am using the C# integration to do the payment, i want to know the minimum lenght of all credit card types to validate in my BLL method.

[mmcguire]

There have been cards issued that are only 12 characters. Most cards are 16 digits. The standard way of validating is to use the Luhn algorithm. There's a lot of free sample code out there with it that you can incorporate.

[NexusSoftware · Accepted solution]

Typically, credit card numbers are all numeric and the length of the credit card number is between 12 digits to 19 digits. 

• 14, 15, 16 digits – Diners Club
• 15 digits – American Express
• 13, 16 digits – Visa
• 16 digits - MasterCard  

For C#, the following validates a credit card number using the Luhn (Mod 10 algorithm):

public static bool Mod10Check(string creditCardNumber)
{
    if (string.IsNullOrEmpty(creditCardNumber))
    {
        return false;
    }

    int sumOfDigits = creditCardNumber.Where((e) => e >= '0' && e <= '9')
                    .Reverse()
                    .Select((e, i) => ((int)e - 48) * (i % 2 == 0 ? 1 : 2))
                    .Sum((e) => e / 10 + e % 10);


 
    return sumOfDigits % 10 == 0;            
}