C#之委托学习二

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

namespace DelegateDemo1
{
    class Program
    {
        /// <summary>
        /// 定义一个返回string，没有参数的委托  delegate:委托关键字
        /// </summary>
        /// <returns></returns>
        delegate string GetAString();
        /// <summary>
        /// 定义一个没有返回值，带一个int类型参数的委托
        /// </summary>
        /// <param name="x"></param>
        delegate void IntMethodInvokder(int x);
        /// <summary>
        /// 定义一个返回double,带2个参数的委托  定义委托：等同于定义一个新类
        /// </summary>
        /// <param name="first"></param>
        /// <param name="second"></param>
        /// <returns></returns>
        delegate double TwoLongOp(long first, long second);


        delegate double DoubleOp(double x);


        static void ProcessAndDisplayNumber(Action<double> action, double value)
        {
            action(value);
        }

        static void Main(string[] args)
        {
            //测试多播委托
            Action<double> operations = MathOperations.MultiplyByTwo;
            operations += MathOperations.Squre;
            //会执行委托的所有方法 MathOperations.MultiplyByTwo、MathOperations.Squre都会被执行 执行的方式是按照顺序执行的
            ProcessAndDisplayNumber(operations, 3);
            ProcessAndDisplayNumber(operations, 4);

            Console.ReadKey();
        }
    }

    class MathOperations
    {
        public static void MultiplyByTwo(double value)
        {
            Console.WriteLine("MultiplyByTwo: " + value * 2);
        }

        public static void Squre(double value)
        {
            Console.WriteLine("Squre: " + value * value);
        }
    }
}