算法

 http://www.cnblogs.com/cj723/archive/2006/08/31/491022.html 

class Program    {        static void Main(string[] args)        {            try            {                Console.Write("请输入数字A：");                string strNumberA = Console.ReadLine();                Console.Write("请选择运算符号(+、-、*、/)：");                string strOperate = Console.ReadLine();                Console.Write("请输入数字B：");                string strNumberB = Console.ReadLine();                string strResult = "";                strResult = Convert.ToString(Operation.GetResult(Convert.ToDouble(strNumberA),Convert.ToDouble(strNumberB),strOperate));                 Console.WriteLine("结果是：" + strResult);                Console.ReadLine();            }            catch (Exception ex)            {                Console.WriteLine("您的输入有错：" + ex.Message);            }        }    }    public class Operation    {        public static double GetResult(double numberA,double numberB,string operate)        {            double result = 0d;            switch (operate)            {                case "+":                    result = numberA + numberB;                    break;                case "-":                    result = numberA - numberB;                    break;                case "*":                    result = numberA * numberB;                    break;                case "/":                    result = numberA / numberB;                    break;            }            return result;        }    }