WDX C# Credit Card Validation Functions

using System;
using System.Collections;
using System.IO;
using System.Data;

namespace WDX.Utilities
{
    public class Payment
    {

        public static bool IsLUHNValid(string ccNo) 
        { 
            bool isValid = false;
            int indicator = 1; // will be indicator for every other number 
            int firstNumToAdd = 0; // will be used to store sum of first set of numbers 
            int secondNumToAdd = 0; // will be used to store second set of numbers 
            string num1; // will be used if every other number added is greater than 10, store the left-most integer here 
            string num2; // will be used if ever yother number added is greater than 10, store the right-most integer here 

            // Convert our creditNo string to a char array 
            char[] ccArr = ccNo.ToCharArray(); 

            if (IsNumeric(ccNo))
            {
                for (int i=ccArr.Length-1;i>=0;i--) 
                { 
                    char ccNoAdd = ccArr[i]; 
                    int ccAdd = Int32.Parse(ccNoAdd.ToString()); 
                    if (indicator == 1) 
                    { 
                        // If we are on the odd number of numbers, add that number to our total 
                        firstNumToAdd += ccAdd; 
                        // set our indicator to 0 so that our code will know to skip to the next piece 
                        indicator = 0; 
                    } 
                    else 
                    { 
                        // if the current integer doubled is greater than 10 
                        // split the sum in to two integers and add them together 
                        // we then add it to our total here 
                        if ((ccAdd + ccAdd) >= 10) 
                        { 
                            int temporary = (ccAdd + ccAdd); 
                            num1 = temporary.ToString().Substring(0,1); 
                            num2 = temporary.ToString().Substring(1,1); 
                            secondNumToAdd += (Convert.ToInt32(num1) + Convert.ToInt32(num2)); 
                        } 
                        else 
                        { 
                            // otherwise, just add them together and add them to our total 
                            secondNumToAdd += ccAdd + ccAdd; 
                        } 
                        // set our indicator to 1 so for the next integer we will perform a different set of code 
                        indicator = 1; 
                    } 
                } 
                // If the sum of our 2 numbers is divisible by 10, then the card is valid. Otherwise, it is not 
                if ((firstNumToAdd + secondNumToAdd) % 10 == 0) 
                { 
                    isValid = true; 
                } 
                else 
                { 
                    isValid = false; 
                }
            }
            else
                isValid = false;

            return isValid; 
        } 


        public enum CardType
        {
            Invalid,
            Unknown,
            AmericanExpress,
            Bankcard,
            DinersClubInternational,
            DinersClubUSandCanada,
            DiscoverCard,
            JCB,
            Maestro,
            MasterCard,
            SoloDebit,
            SwitchDebit,
            Visa,
            VisaElectron,
            enRoute
        }

        public static CardType GetCardType(string strCardNumber)
        {
            strCardNumber = strCardNumber.Replace(" ", "");

            // Check American Express
            if (strCardNumber.Substring(0, 2)=="34" || strCardNumber.Substring(0, 2)=="37")
            {
                if (strCardNumber.Length==15)
                    return CardType.AmericanExpress;
                else
                    return CardType.Invalid;
            }

            // Check Bankcard
            if (strCardNumber.Substring(0, 3).ToUpper() == "DNE") return CardType.Bankcard;

            // Check Diners Club Internationl
            if (strCardNumber.Substring(0, 2) == "36" || strCardNumber.Substring(0, 2) == "38" || (Convert.ToInt32(strCardNumber.Substring(0, 3)) >= 300 && Convert.ToInt32(strCardNumber.Substring(0, 3)) <= 305))
                if (strCardNumber.Length==14)
                    return CardType.DinersClubInternational;
                else
                    return CardType.Invalid;

            // Check Diners Club US and Canadaa
            if (strCardNumber.Substring(0, 2) == "55") return CardType.DinersClubUSandCanada;

            // Check Discover Card
            if (strCardNumber.Substring(0, 4) == "6011") 
                if (strCardNumber.Length==16)
                    return CardType.Bankcard;
                 else
                    return CardType.Invalid;

            // Check JCB Card
            if (strCardNumber.Substring(0, 4) == "2131" || strCardNumber.Substring(0, 4) == "1800" ) 
                if (strCardNumber.Length==15)
                    return CardType.JCB;
                else
                    return CardType.Invalid;

            // Check Maestro Card
            if (strCardNumber.Substring(0, 4) == "5020") 
                if (strCardNumber.Length==16)
                    return CardType.Maestro;
                else
                    return CardType.Invalid;

            // Check MasterCard
            if ((Convert.ToInt32(strCardNumber.Substring(0, 3)) >= 51 && Convert.ToInt32(strCardNumber.Substring(0, 3)) <= 55)) 
                if (strCardNumber.Length==16)
                    return CardType.MasterCard;
                else
                    return CardType.Invalid;

            // Check Solo Card
            if (strCardNumber.Substring(0, 2) == "63" || strCardNumber.Substring(0, 4) == "6767") 
                if (strCardNumber.Length==16 || strCardNumber.Length==18 || strCardNumber.Length==19)
                    return CardType.SoloDebit;
                else
                    return CardType.Invalid;

            // Check Switch Card
            if (strCardNumber.Substring(0, 4) == "4903" || strCardNumber.Substring(0, 4)== "4905" || strCardNumber.Substring(0, 4) == "4911" || strCardNumber.Substring(0, 4) == "4936" || strCardNumber.Substring(0, 6) == "564182" || strCardNumber.Substring(0, 6) == "633110" || strCardNumber.Substring(0, 4) == "6333" || strCardNumber.Substring(0, 4) == "6759") 
                if (strCardNumber.Length==16 || strCardNumber.Length==18 || strCardNumber.Length==19)
                    return CardType.SwitchDebit;
                else
                    return CardType.Invalid;

            // Check Visa Electron Card
            if (strCardNumber.Substring(0, 6) == "417500") 
                if (strCardNumber.Length==16)
                    return CardType.VisaElectron;
                else
                    return CardType.Invalid;

            // Check Visa Card
            if (strCardNumber.Substring(0, 1) == "4") 
                if (strCardNumber.Length==16)
                    return CardType.Visa;
                else
                    return CardType.Invalid;

            // Check enRoute Card
            if (strCardNumber.Substring(0, 4) == "2014" || strCardNumber.Substring(0, 4) == "2149") 
                if (strCardNumber.Length==15)
                    return CardType.enRoute;
                else
                    return CardType.Invalid;

            return CardType.Unknown;

        }
    }
}