代码1：

using System;

namespace DelegateDemo
{ 
    public class Secretary
    {
        public void BuyAirlineTicket(int count)
        {
            Console.WriteLine("购买{0}张飞机票。", count);
        }
        public void BookHotel(int star)
        {
            Console.WriteLine("订{0}星级酒店。", star);
        }
        public void BuyTripBag(string name)
        {
            Console.WriteLine("购买{0}牌旅行包。", name);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Secretary sec = new Secretary();
            Action<int> ctripAction= new Action<int>(sec.BuyAirlineTicket);
            ctripAction(2);
            ctripAction = new Action<int>(sec.BookHotel);
            ctripAction(5);
            Action<string> taobaoAction = new Action<string> (sec.BuyTripBag);
            taobaoAction("航天");
        }
    }
}

代码2：

using System;

namespace DelegateDemo
{
    public class Secretary
    {
        private int _count;
        private int _star;
        private string _name;
        public Secretary(int count, int star, string name)
        {
            _count = count;
            _star = star;
            _name = name;
        }
        public void BuyAirlineTicket()
        {
            Console.WriteLine("购买{0}张飞机票。", _count);
        }
        public void BookHotel()
        {
            Console.WriteLine("订{0}星级酒店。", _star);
        }
        public void BuyTripBag()
        {
            Console.WriteLine("购买{0}牌旅行包。", _name);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Secretary sec = new Secretary(2,5,"航天");
            Action action = new Action(sec.BuyAirlineTicket);          
            action+= new Action(sec.BookHotel);        
            action+= new Action(sec.BuyTripBag);
            action();
        }
    }
}

代码3：

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 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);
            ctripAction(2,5);
            Func<string, string> taobaoFun = new Func<string, string>(sec.BuyTripBag);
            Console.WriteLine(taobaoFun("航天"));          
        }
    }
}