知识是通向未来的桥梁
博客是管理知识的手段

1.普通用法

using System;
namespace DelegateDemo
{
   public class Secretary
   {    

       public void BuyAirlineTicketAndBookHotel(int count,int star)
       {
           Console.WriteLine("购买{0}张飞机票,订{1}星级酒店。", count,star);
       }       
       public static string BuyTripBag(string name)
       {
           Console.WriteLine("购买{0}牌旅行包。", name);
           return "购包成功!";
       }
   }
   class Program
   {
       static void Main(string[] args)
       {
           Secretary sec = new Secretary();
           Action<int,int> ctripAction = new Action<int,int>(sec.BuyAirlineTicketAndBookHotel);
           Func<string, string> taobaoFun = new Func<string, string>(Secretary.BuyTripBag);

           //方法1:
           //ctripAction(2,5);
           //Console.WriteLine(taobaoFun("航天"));

           //方法2:
           //ctripAction.Invoke(2, 5);
           //Console.WriteLine(taobaoFun.Invoke("航天"));

           //方法3:
           ctripAction?.Invoke(2, 5);
           Console.WriteLine(taobaoFun?.Invoke("航天"));


       }
   }
}

2.回调用法

using System;
namespace DelegateDemo
{
   public class MathOp
   {
       public void Add(int x, int y, Action<int> call)
       {
           if (call != null)
           {
               call(x + y);
           }
       }
       public void Add(int x, int y, Func<int,int> call)
       {
           if (call != null)
           {
               Console.WriteLine("结果是:{0}", call(x + y));
           }
       }
   }
   class Program
   {
       static void Main(string[] args)
       {
           MathOp mathOp = new MathOp();
           mathOp.Add(1, 2, CallPrint);
           mathOp.Add(10,20,CallReturn);
           Console.ReadKey();
       }
       private static void CallPrint(int res)
       {
           Console.WriteLine("结果是：" + res);
       }
       private static int CallReturn(int res)
       {
           return res;          
       }
   }
}