C#实现身份证号码校验的类

public class CardValidator
    {
        private const int Divisor = 11;
        private const int MinLen = 17;
        private static readonly List<int>  Factors=new List<int>()
        {
            7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2
        };
        private static readonly Dictionary<int,string> Result=new Dictionary<int, string>()
        {
            {0,"1"},{1,"0"},{2,"X"},{3,"9"},{4,"9"},{5,"7"},{6,"6"},{7,"5"},{8,"4"},{9,"3"},{10,"2"}
        }; 
        private static readonly List<int> Products=new List<int>(); 

        public static bool IsValid(string cardNo)
        {
            if (string.IsNullOrEmpty(cardNo) || cardNo.Length <MinLen)
            {
                return false;
            }

            var subCard = cardNo.Substring(0, MinLen);
            for (var i=0;i<subCard.Length;i++)
            {
                int c;
                if (!int.TryParse(subCard.Substring(i,1), out c))
                {
                    return false;
                }
                Products.Add(c*Factors[i]);
            }

            var sum = Products.Sum();
            var mod = sum%Divisor;
            var val = Result[mod];

            return val == cardNo.Substring(cardNo.Length - 1, 1);
        }
    }