23-入门详解

委托的使用

 class Program
    {
        static void Main(string[] args)
        {
            MyDele dele1 = new MyDele(M1);
            Student stu = new Student();
            dele1 += stu.SayHello;
            dele1.Invoke();
        }
        static void M1() {
            Console.WriteLine("M1 is called");
        }
    }
    class Student
    {
        public void SayHello()
        {
            Console.WriteLine("Hello,I'm a student!");
        }
    }
    delegate void MyDele();

 class Program
    {
        static void Main(string[] args)
        {
            MyDele dele1 = new MyDele(Add);
            int res = dele1(100, 200);
            Console.WriteLine(res);
        }
        static int Add(int x,int y) {
            return x + y;
        }
    }
    delegate int MyDele(int a,int b);

泛型委托

 MyDele<int> deleAdd = new MyDele<int>(Add);
            int res = deleAdd(100, 200);
            Console.WriteLine(res);
            MyDele<double> deleMul = new MyDele<double>(Mul);
            double mulRes = deleMul(3.0, 5.0);
            Console.WriteLine(mulRes);
            Console.WriteLine(deleAdd.GetType().IsClass);
        }
        static int Add(int x,int y)
        {
            return x + y;
        }
        static double Mul(double x,double y)
        {
            return x * y;
        }
    }
    delegate T MyDele<T>(T a, T b);

运用类库直接委托不用声明

 class Program
    {
        static void Main(string[] args)
        {
            Action action = new Action(M1);
            action();
            Action<string> action2= new Action<string>(SayHello);
            action2("Tim");
            Func<int, int, int> func = new Func<int, int, int>(Add);
            int res = func(100, 200);
            Console.WriteLine(res);
        }
        static void M1()
        {
            Console.WriteLine("M1 is called!");
        }
        static void SayHello(string name)
        {
            Console.WriteLine("Hello,{0}",name);
        }
        static int Add(int x,int y)
        {
            return x + y;
        }
        static double Mul(double x,double y)
        {
            return x * y;
        }
    }

有返回值用Func<>，无返回值用Action<>。

Lambda表达式

 class Program
    {
        static void Main(string[] args)
        {
            Func<int, int, int> func = new Func<int, int, int>((int a, int b) => { return a + b; });
            int res = func(100, 200);
            Console.WriteLine(res);
            func = new Func<int, int, int>((int x, int y) => { return x * y});
            res = func(3, 4);
            Console.WriteLine(res);
        }
    }

 class Program
    {
        static void Main(string[] args)
        {
            Func<int, int, int> func = ((int a, int b) => { return a + b; });
            int res = func(100, 200);
            Console.WriteLine(res);
            func =((int x, int y) => { return x * y; });
            res = func(3, 4);
            Console.WriteLine(res);
        }
    }

泛型方法+泛型委托类参数+

 class Program
    {
        static void Main(string[] args)
        {
           // DoSomeCalc<int>((int a, int b)=>{ return a * b; }, 100, 200);
            DoSomeCalc(( a,  b) => { return a * b; }, 100, 200);//100,200可以推断出来是整型，所以int可以省略
        }
        static void DoSomeCalc<T>(Func<T, T, T> func, T x, T y)
        {
          T  res=func(x, y);
            Console.WriteLine(res);
        }
    }