策略模式的簡單應用（C#）

 using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
   abstract  class OperSuper
    {
       public  abstract   double GetResult(double a,double b);
    }

    class Add:OperSuper
    {
        public  override  double GetResult(double a, double b)
        {
            return a + b;
        }
    }

    class Minus : OperSuper
    {
        public  override  double GetResult(double a, double b)
        {
            return a - b;
        }
    }

    class Context
    {
        OperSuper os = null;
        double A,B;
       public  Context(OperSuper o,double a,double b)
        {
            os = o;
            A = a;
            B = b;
        }

        public  double  GetResult()
        {
            return os.GetResult(A,B);
        }
    }

    class client
    {
        public static void Main()
        {
            Context c = new Context(new Add(), 10, 20);
            Console.WriteLine(c.GetResult ());
            c = new Context(new Minus(), 20, 10);
            Console.WriteLine(c.GetResult());
        }
    }
}