說一下用c#編寫的無限位數計算

閒來沒事有點無聊，記得以前搞acm時經常用c來寫無限位數的加減計算，那乘除呢？我現在就用c#寫了一個：

加法和減法簡單，就是用一個數組來保存每一位上的數字，然後從後往前一位一位的加減，加法記得前面會進一，減法則要把前面多余的“0”去掉；

乘法，你就在草稿紙上做下筆算吧，就是兩個數組相應位數撒謊能夠的數字相乘，分別在後面加上這兩個數位後面的“0”，比如：

          234*678=2*6*100*100+2*7*100*10+。。。。+4*8

是否看的明白？就是小學時老師怎麼教你算你就怎麼算，把電腦當成小學生就行了，這裡要用到前面的加法；

除法：先拿被除數前面和除數相同位數的數和除數的倍數進行比較，這裡的倍數計算就是前面的乘法，把最大倍數放進答案的最高位，以此類推，再把余下的數*10+後面一位，繼續計算，直到最後一位；

下面是我寫的代碼，我先貼出最底層的無符號無浮點運算，計算參數均為StringBuilder類型，方便轉換

（此代碼僅供參考，不得參與商業活動）

static internal class Calculate
    {
        static private int[] operand1;
        static private int[] operand2;
        static private IList<int> result;

        /// <summary>
        /// 加法
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        static internal StringBuilder Addition(StringBuilder a, StringBuilder b)
        {
            SetOperand(a, b);

            try
            {
                Reverse();
                int count = (operand1.Length > operand2.Length) ? operand1.Length : operand2.Length;
                int op1, op2, upNum = 0;
                for (int i = 0; i < count; i++)
                {
                    op1 = (i >= operand1.Length) ? 0 : operand1[i];
                    op2 = (i >= operand2.Length) ? 0 : operand2[i];
                    int temp = op1 + op2 + upNum;
                    if (temp < 10)
                    {
                        result.Insert(0, temp);
                        upNum = 0;
                    }
                    else
                    {
                        result.Insert(0, temp % 10);
                        upNum = temp / 10;
                    }
                    if ((i == (count - 1)) && upNum > 0) result.Insert(0, upNum);
                }
            }
            catch { result = new List<int>() { 0,0,0}; }

            return GetResult();
        }

        /// <summary>
        /// 減法
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        static internal StringBuilder Subtraction(StringBuilder a, StringBuilder b)
        {
            SetOperand(a, b);
           
            try
            {
                Reverse();
                bool desc = isDesc(a, b);
                int[] opList1 = desc ? operand2 : operand1;
                int[] opList2 = desc ? operand1 : operand2;
                int count = (opList1.Length > opList2.Length) ? opList1.Length : opList2.Length;
                int op1, op2, upNum = 0;
                for (int i = 0; i < count; i++)
                {
                    op1 = (i >= opList1.Length) ? 0 : opList1[i];
                    op2 = (i >= opList2.Length) ? 0 : opList2[i];
              &