C#编写的windows计算器-源代码

C#编写的windows计算器-源代码(33)                     res = tmp * tmp;                   
                    break;
                    // 平方根
                case SQRT:
                    res = System.Math.Sqrt(tmp);                   
                    break;
                default:
                    return;
            }
            txtShow.Text = res.ToString();   //结果输出到文本显示屏
            opt = NULL;  //运算符清空
            tmp=0;   
            dot = NODOT;
                    //res = 0;
                    //num = 0;
        }
        #endregion

        #region 获取操作符运事件