知识是通向未来的桥梁
博客是管理知识的手段

using System;

namespace delegateDemo
{
   class Program
   {
       public delegate void OneParaArea(int p);      

       static void Main(string[] args)
       {
           //1:传统方法
           CircleArea(10);
           SquareArea(10);
           //2:下面都是委托类的各种变化
           OneParaArea opa = new OneParaArea(CircleArea);
           opa(10);
           opa = new OneParaArea(SquareArea);
           opa(10);
           //3
           OneParaArea opb1 = new OneParaArea(radius=>
           {
               Console.WriteLine(Math.PI * radius * radius);
           });
           opb1(10);
           OneParaArea opb2 = new OneParaArea(size =>
           {
               Console.WriteLine( size * size);
           });
           opb2(10);
           //4
           Action<int> OneParaAction;
           OneParaAction = CircleArea;
           OneParaAction(10);
           OneParaAction = SquareArea;
           OneParaAction(10);
           //5
           Action<int> OneParaActionB;
           OneParaActionB = radius =>
           {
               Console.WriteLine(Math.PI * radius * radius);
           };
           OneParaActionB(10);

           OneParaActionB = size =>
           {
               Console.WriteLine(size * size);
           };
           OneParaActionB(10);
       }

       static void CircleArea(int radius)
       {
           Console.WriteLine(Math.PI*radius*radius);
       }
       static void SquareArea(int s)
       {
           Console.WriteLine(s * s);
       }

   }
}