20进制数据加法

        /// <summary>

        /// 计算20进制
        /// </summary>
        /// <param name="x">参数1</param>
        /// <param name="y"></param>
        /// <returns>20进制结果</returns>
        public static string getRes(string x, string y)
        {
            //定义1-19
            string [] ca = {"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j" };
            char[] a = x.ToCharArray();
            char[] b = y.ToCharArray();
            //检验格式是否正确
            foreach (char ah in a)
            {
                if (!ca.Contains(ah.ToString()))
                {
                    MessageBox.Show("字符" + x + "格式错误");
                    break;
                }

            }
            foreach (char ah in b)
            {
                if (!ca.Contains(ah.ToString()))
                {
                    MessageBox.Show("字符" + y + "格式错误");
                    break;
                }

            }
            //参数长度  使len2a 大于等于len2b
            int len2a = a.Length;
            int len2b = b.Length;
            if (len2a < len2b)
            {
                //数组交换
                len2a = b.Length;
                len2b = a.Length;
                a = y.ToCharArray();
                b = x.ToCharArray();
            }
            
            //结果
               string[] res = new string[len2a + 1];
                res[len2a] = "0";
                //数据长度长的和数据长度短的各对应位数的 数值相加
                for (int i = len2a - 1, j = len2b - 1; j >= 0; i--, j--)
                {
                    int m = Array.IndexOf(ca, a[i].ToString()) + Array.IndexOf(ca, b[j].ToString())+Int32.Parse( res[i+1]);
                    if (m >= 20)
                    {
                        res[i + 1] = ca[m - 20];
                        res[i] = Int32.Parse(ca[1]).ToString();
                    }
                    else
                    {
                        res[i + 1] = ca[m];
                        res[i] = "0";
                    }

                }
                 //数据长度长的多余的位数直接赋值给结果数组
                for (int i = len2a - len2b-1; i >= 0;i-- )
                {
                    int m = Array.IndexOf(ca, a[i].ToString()) + Int32.Parse(res[i + 1]);
                    if (m >= 20)
                    {
                        res[i + 1] = ca[m - 20];
                        res[i] = Int32.Parse(ca[1]).ToString();
                    }
                    else
                    {
                        res[i + 1] = ca[m];
                        res[i] = "0";
                    }
                }
                string resoult="";
                //去掉首位0
                if (!res[0].Equals("0"))
                {
                    resoult = res[0];
                }
                for(int i=1;i<res.Length;i++){

                    resoult += res[i];
                }

                return resoult;

        }

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