class Program
    {
        static void Main(string[] args)
        {
            Operation oper;
            oper = OperationFactory.CreateOperation("4");
            if(oper!=null)
            {
                oper.NumberA = 1;
                oper.NumberB = 2;

                Console.WriteLine(oper.GetResult());
            }
            Console.ReadLine();
        }
    }

    #region //简单工厂类
    public class OperationFactory
    {
        public static Operation CreateOperation(string operation)
        {
            Operation oper = null;
            switch (operation)
            {
                case "+":
                    oper = new OperationAdd();
                    break;
                case "-":
                    oper = new OperationSub();
                    break;
                case "*":
                    oper = new OperationMul();
                    break;
                case "/":
                    oper = new OperationDiv();
                    break;
            }

            return oper;


        }
    }
    #endregion

    #region//运算类Operation
    public class Operation
    {
        private double _numberA = 0;
        private double _numberB = 0;

        public double NumberA
        {
            get 
            {
                return _numberA;
            }
            set
            {
                _numberA = value;
            }
        }


        public double NumberB
        {
            get
            {
                return _numberB;
            }
            set
            {
                _numberB = value;
            }
        }


        public virtual double GetResult()
        {
            double result = 0;
            return result;
        }
    }
    #endregion

    #region//继承运算类
    public class OperationAdd : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA + NumberB;
            return result;
        }
    }

    public class OperationSub : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA - NumberB;
            return result;
        }
    }

    public class OperationMul : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA * NumberB;
            return result;
        }
    }

    public class OperationDiv : Operation
    {
        public override double GetResult()
        {
            double result = 0;
            result = NumberA / NumberB;
            return result;
        }
    }
    #endregion