C#之委托

委托就是第三方,调用者告诉第三方要做什么,然后调用者就不用管了 这个委托(第三方)就会去调用方法去帮你实现
委托的好处:

1.相当于用方法作为另一方法参数(类似于C的函数指针)

2.在两个不能直接调用的方法中作为桥梁,如:在多线程中的跨线程的方法调用就得用委托

3.当不知道方法具体实现什么时使用委托,如:事件中使用委托

先看个例子，中国人打招呼，和英国人打招呼的一般写法

        static void Main(string[] args)
        {
            SayHiChinese("Jim");
            SayHiEnglish("Jim");
            Console.Read();  
        }
        public static void SayHiChinese(string name)
        {
            Console.WriteLine("吃饭了吗 {0}",name);
        }
        public static void SayHiEnglish(string name)
        {
            Console.WriteLine("Nice to meet you {0}",name);
        }    

再看下委托

        //定义一个委托
        public delegate void SayHi(string name);
        static void Main(string[] args)
        {
            //SayHi SHZh = new SayHi(SayHiChinese);
            SayHi SHZh = SayHiChinese;
            SHZh("Jim");
            //SayHi SHEn = new SayHi(SayHiEnglish);
            SayHi SHEn = SayHiEnglish;
            SHEn("Jim");
            Console.Read();  
        }
        public static void SayHiChinese(string name)
        {
            Console.WriteLine("吃饭了吗 {0}",name);
        }
        public static void SayHiEnglish(string name)
        {
            Console.WriteLine("Nice to meet you {0}",name);
        }

或者

        //定义一个委托
        public delegate void SayHi(string name);
        static void Main(string[] args)
        {
            test("Jim", SayHiChinese);
            test("Jim", SayHiEnglish);
            Console.Read();
        }

        private static void test(string name, SayHi SH)
        {
            SH(name);
        }

        public static void SayHiChinese(string name)
        {
            Console.WriteLine("吃饭了吗 {0}",name);
        }
        public static void SayHiEnglish(string name)
        {
            Console.WriteLine("Nice to meet you {0}",name);
        }    

结果都是

匿名函数

         //定义一个委托
        public delegate void SayHi(string name);
        static void Main(string[] args)
        {
            SayHi SH = delegate (string name)
                {
                    Console.WriteLine("你好 "+ name);
                };
            SH("Jim");   
            Console.Read();
        }

lamda表达式

        //定义一个委托
        public delegate void SayHi(string name);
        static void Main(string[] args)
        {
            SayHi SH = (string name) => { Console.WriteLine("你好"+name); };
            SH("Jim");
            Console.Read();
        }