C# lambda+委托

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

namespace learn_lambda2
{
    internal class Program
    {
        static void Main(string[] args)
        {

            // 单行, 无参数, 无返回值
            Action action = () => { Console.WriteLine("hello world"); };
            action();

            // 多行, 两个参数, 无返回值
            Action<int, string> action1 = new Action<int, string>((a, b)=> {
                a += a;
                Console.WriteLine($"{a} + {b}"); 
            });
            action1(123, "123");

            // 单行, 无参数, 有返回值
            Func<int> action2 = () => { return 123; };
            Console.WriteLine(action2());

            // 多行, 两个参数, 有返回值
            Func<int, string, int> action3 = new Func<int, string, int>((a, b) =>
            {
                a += a;
                return Convert.ToInt32(b) + a;
            });
            Console.WriteLine(action3(123, "123"));

            Console.ReadKey();
        }
    }
}

执行结果

hello world
246 + 123
123
369