C#版 大数计算器乘法

class BigMultiply:BigCalculate
 

   {
        public override string Oper(string num1, string num2)
        {
            if (num1.Equals("0")||num2.Equals("0"))
            {
                return "0";
            }

            List liAllNum = new List();//存储乘数每位乘法的结果
            List liCh = new List();//存储乘数每位乘法中每一位的结果

            //将长度较长的数字赋给num1，方便后面计算
            if (num1.Length < num2.Length)
            {
                ChangeNum(ref num1, ref num2);
            }
 
            int flag;
            for (int i = num2.Length-1; i >=0; i--)
            {
                //初始化上一位乘法中的数据
                liCh.Clear();
                flag = 0;
                //计算第i位乘以第j位
                for (int j = num1.Length - 1; j >= 0; j--)
                {
                    liCh.Add((char)((num2[i] - '0') * (num1[j] - '0')+flag+'0'));
                    flag = (liCh[liCh.Count-1] -'0')/ 10;
                    liCh[liCh.Count - 1] = (char)((liCh[liCh.Count - 1] - '0') % 10+'0');
                }
                //若进位不为0，则在加进位
                if (flag>0)
                {
                    liCh.Add((char)(flag+'0'));
                }
                //添加结果集
                liAllNum.Add(InvertOrder(new string(liCh.ToArray()))+new string('0',liAllNum.Count));
            }
            int count = 0;
            string res="0";
            //调用add方法，将每一位乘法所得的结果相加，即为结果
            BigAdd addOper= new BigAdd();
            while (count
            {
                res = addOper.Oper(res,liAllNum[count]);
                count++;
            }

            return res;  
        }
}