C# - 委托

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

namespace 委托2
{
    class Program
    {
       /// <summary>
       ///      声明委托: 委托的返回值类型、参数类型、参数个数必须与被委托函数保持一致。
       /// </summary>
        /// <param name="x"> 参与运算的数据 </param>
        /// <param name="y"> 参与运算的数据 </param>
       /// <returns></returns>
        delegate double Calculate(double x, double y);
        static void Main(string[] args)
        {
            Console.WriteLine( "委托: Add 运算结果: {0}", DoCal(Add, 5, 2) );
            Console.WriteLine( "委托: Sub 运算结果: {0}", DoCal(Sub, 6, 3) );
            Console.WriteLine( "委托: Mul 运算结果: {0}", DoCal(Mul, 10, 2) );
            Console.WriteLine( "委托: Dev 运算结果: {0}", DoCal(Dev, 20, 2) );

            Console.ReadLine();
        }

        /// <summary>
        ///     执行运算
        /// </summary>
        /// <param name="cal"> 委托类型形参 </param>
        /// <param name="x"> 参与运算的数据 </param>
        /// <param name="y">参与运算的数据 </param>
        /// <returns> 返回被委托函数的运算结果 </returns>
        static double DoCal(Calculate cal, double x, double y)
        {
            return cal(x, y);
        }
        // 加法
        static double Add(double x, double y)
        {
            return x + y;
        }
        // 减法
        static double Sub(double x, double y)
        {
            return x - y;
        }
        // 乘法
        static double Mul(double x, double y)
        {
            return x * y;
        }
        // 除法
        static double Dev(double x, double y)
        {
            return x / y;
        }

    }
}