Get the Credit Card Type based on Number

Question

Before you mark this as answered in another post (I already saw those). But in none of them they specifically say the REGEX they suggest works for C# (I think they focus more on Javascript). Now I am not too good with regex but I would appreciate any help determining how to get the type and once I get the regex how can I validate the cc entered against the regex?

I saw this as an answer in many of the posts here in StackOverflow, but would this work in C# (same code) if yes how can i compare my creditCard string to the regex?

Get Card Type based on number

I would really appreciate any help, this is the first time i deal with credit card validation, just need to get the type. Drop down is out of the question based on the feedback from the person needing it.

Answer 1

Here is a fuller answer for the next guy.

    public enum CardType
    {
        MasterCard, Visa, AmericanExpress, Discover, JCB
    };

    public static CardType FindType(string cardNumber)
    {
        //https://www.regular-expressions.info/creditcard.html
        if (Regex.Match(cardNumber, @"^4[0-9]{12}(?:[0-9]{3})?$").Success)
        {
            return CardType.Visa;
        }

        if (Regex.Match(cardNumber, @"^(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}$").Success)
        {
            return CardType.MasterCard;
        }

        if (Regex.Match(cardNumber, @"^3[47][0-9]{13}$").Success)
        {
            return CardType.AmericanExpress;
        }

        if (Regex.Match(cardNumber, @"^6(?:011|5[0-9]{2})[0-9]{12}$").Success)
        {
            return CardType.Discover;
        }

        if (Regex.Match(cardNumber, @"^(?:2131|1800|35\d{3})\d{11}$").Success)
        {
            return CardType.JCB;
        }

        throw new Exception("Unknown card.");
    }


    //test validation
    //https://www.getcreditcardnumbers.com/
    Validate("4169773331987017");//visa
    Validate("4658958254583145");//visa
    Validate("4771320594033780");//visa

    Validate("5410710000901089");//mc
    Validate("5289675573349651");//mc
    Validate("5582128534772839");//mc

    Validate("349101032764066");//ae
    Validate("343042534582349");//ae
    Validate("371305972529535");//ae

    Validate("6011683204539909");//discover
    Validate("6011488563514596");//discover
    Validate("6011465836488204");//discover

    Validate("3529908921371639");//jcb
    Validate("3589295535870728");//jcb
    Validate("3569239206830557");//jcb