C# 委托

一、委托

1、Action

new Action(方法);

委派：无返回值

2、FunC

委派：有返回值

new Func<参数类型和返回值类型>(方法);

using Mysqlx.Notice;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ClassAndIn
{
    internal class Program
    {
        static void Main(string[] args)
        {

            Calculation calculation = new Calculation();

            // action 没有返回值
            Action action = new Action(calculation.Print);
            action(); // 执行

            // Func
            // <> 里面是参数类型和返回值类型
            Func<int, int, int> func = new Func<int, int, int>(calculation.Add);
            // 使用
            int a = 10;
            int b = 20;
            int c = 0;
            c = func(a, b);
            Console.WriteLine("{0}+{1}={2}", a, b, c);
        }


        

    }

    class Calculation
    {
        public void Print() 
        {
            Console.WriteLine("Hello, World!");
        }

        public int Add(int x, int y) 
        {
            return x + y;
        }

        public int Sub(int x, int y) 
        {
            return x- y;    
        }

    }
   


}

二、自定义委托

1、语法

a、定义

pulic delegate 返回值类型 委托名(参数类型);

b、执行

委托名 变量名 = new 委托名()

2、案例

using Mysqlx.Notice;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ClassAndIn
{
    // 声明委托
    public delegate double Cal(double a, double b);
    internal class Program
    {
        
        static void Main(string[] args)
        {
            Calculator calculator = new Calculator();
            // 调用委托
            Cal cal1 = new Cal(calculator.Add);
            double x = 20;
            double y = 40;
            double z = 0;
            z = cal1(x, y);
            Console.WriteLine(z);
        }
    }

    class Calculator
    {
        public double Add(double x, double y) 
        {
            return x + y;
        }

        public double Sub(double x, double y)
        { 
            return x - y;
        }

        public double Mul(double x, double y) 
        {
            return x * y;
        }

        public double Div(double x, double y)
        {
            return x / y;
        }
    }
}