委托

委托就像一个占位符"{0}"，等待传入一个具体的方法

委托又好像只定义了一个方法的接口，等待具体的实现

namespace ConsoleApplication1
{
    //c#1定义委托
    public delegate int CalculatorDelegate(int a, int b);
    //c#2支持泛型
    public delegate TResult MyFunc<T1, T2, TResult>(T1 a, T2 b);
    class Program
    {
        static void Main(string[] args)
        {
            Calculator cal = new Calculator();
            //c#1
            CalculatorDelegate calculatorDelegate1 = new CalculatorDelegate(cal.Add);
            //c#2不需要new
            CalculatorDelegate calculatorDelegate2 = cal.Add;
            //c#2支持匿名方法
            MyFunc<int, int, int> myFun2 = delegate (int a, int b) { return a + b; };
            //c#3支持lambda
            MyFunc<int, int, int> myFun3 = (a, b) => a + b;

            int c = calculatorDelegate1(1, 2);
        }
    }
    public class Calculator
    {
        public int Add(int a, int b)
        {
            return a + b;
        }
    }
}