编辑代码

using System;
public delegate double Calc(double x, double y);
public class HelloWorld
{
    public static void Main()
    {
       Calculator calc = new Calculator();
       Calc c1 = new Calc(calc.Add);
       Calc c2 = new Calc(calc.Sub);
       Calc c3 = new Calc(calc.Mul);
       Calc c4 = new Calc(calc.Div);
       
       double a = 100;
       double b =200;
       double c = 0;

       c = c1(a,b);
       Console.WriteLine(c);
       c = c2.Invoke(a,b);
       Console.WriteLine(c);
       c = c3(a,b);
       Console.WriteLine(c);
       c = c4.Invoke(a,b);
       Console.WriteLine(c);

    }
}

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;
    }
}