C# 委托和方法

委托是一种特殊的引用类型，它将方法也作为特殊的对象封装起来，从而将方法作为变量或参数进行传递

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    delegate void DualFunction(double x,double y);
    class Program
    {
        static void Main()
        {
            DualFunction fun1;
            double a = 2.5, b = 2;
            Console.WriteLine("请选择函数（加0减1乘2除3）:");
            int i = int.Parse(Console.ReadLine());
            if (i == 1)
                fun1 = new DualFunction(Sub);
            else if (i == 2)
                fun1 = new DualFunction(Mul);
            else if (i == 3)
                fun1 = new DualFunction(Div);
            else
                fun1 = new DualFunction(Add);
            fun1(a, b);
            Console.ReadLine();
        }
        static void Add(double x,double y)
        {
            Console.WriteLine("{0}+{1}={2}", x, y, x + y);
        }
        static void Sub(double x,double y)
        {
            Console.WriteLine("{0}-{1}={2}", x, y, x - y);
        }
        static void Mul(double x,double y)
        {
            Console.WriteLine("{0}*{1}={2}", x, y, x * y);
        }
        static void Div(double x,double y)
        {
            Console.WriteLine("{0}/{1}={2}", x, y, x / y);
        }
    }
}

DaulFunction fun1=new DualFunction(Sub);

DualFunction fun1=Sub;//这两种方式也行

还可以将委托对象放在数组中  比如

static void Main()
{
DualFunction[] funs = new DualFunction[] { Add, Sub, Mul, Div };
double a=2.5, b=2.0;
Console.WriteLine("请选择函数（加0减1乘2除3）：");
int i = int.Parse(Console.ReadLine());
funs[i](a, b);
Console.ReadLine();
}

一个委托对象还可以封装多个方法   委托对象的合并和删除  比如DualFunction fun1 = funs[1] + funs[2];