WPF学习——C#语言中的委托

参考：C#语言入门详解https://www.bilibili.com/video/BV1wx411K7rb?p=19 刘猛铁

留言区评论笔记https://www.yuque.com/yuejiangliu/dotnet/timothy-csharp-019

C#语言中的委托是函数指针的升级版。

Action 和 Func 是 C# 内置的委托实例，它们都有很多重载以方便使用。

using System;

namespace DelegateExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Calculator calculator = new Calculator();
            Action action = new Action(calculator.Report);      // 委托
            calculator.Report();
            action.Invoke();
            action();

            Func func1 = new Func(calculator.Add);    // 泛型委托
            Func func2 = new Func(calculator.Sub);

            Console.WriteLine(func1(4, 5));
            Console.WriteLine(func2(4, 5));
        }
    }

    class Calculator
    {
        public void Report()
        {
            Console.WriteLine("I have three methods.");
        }

        public int Add(int a,int b)
        {
            return a + b;
        }

        public int Sub(int a,int b)
        {
            return a - b;
        }
    }
}

自定义委托

委托是类，所以声明位置是和 class 处于同一个级别。但 C# 允许嵌套声明类（一个类里面可以声明另一个类），所以有时也会有 delegate 在 class 内部声明的情况。

using System;

namespace DelegateExample
{

    public delegate double fun(double a, double b);

    class Program
    {
        static void Main(string[] args)
        {
            Calculator calculator = new Calculator();
            fun fun1 = new fun(calculator.Add);

            Console.WriteLine(fun1(7,6));
        }
    }

    class Calculator
    {
        public void Report()
        {
            Console.WriteLine("I have three methods.");
        }

        public double Add(double a, double b)
        {
            return a + b;
        }

        public double Sub(double a, double b)
        {
            return a - b;
        }

        public double Mul(double a,double b)
        {
            return a * b;
        }

        public double Div(double a,double b)
        {
            return a / b;
        }
    }
}

委托作为属性

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Calculator calculator = new Calculator();
            Action action1 = new Action(calculator.Report);
            action1.Invoke();

            calculator.ReportAction = new Action(calculator.ReportName);
            calculator.ReportAction("Pocky");

            calculator.AddFunc = new Func(calculator.Add);
            Console.WriteLine(calculator.AddFunc(1, 2));
        }
    }

    class Calculator
    {
        public void Report()
        {
            Console.WriteLine("Come on!");
        }

        public void ReportName(string name)
        {
            Console.WriteLine("My name is ");
            Console.WriteLine(name);
        }

        public int Add(int a,int b)
        {
            return a + b;

        }

        public void Report2(string a)
        {
            if(ReportAction == null)
            {
                return;
            }
            this.ReportAction(a);
        }

        public Action ReportAction { get; set; }

        public Func AddFunc { get; set; }

    }

}

代码：https://download.csdn.net/download/ngany/12663203