C##的基础语法

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

namespace HelloWorld
{
    class Recttest {

        public String test = "My string test";
        public void Testfun() {
            Console.WriteLine("Hello world2");
          
        }
    }

    
    
    class HelloApp
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello world1");

            Recttest r = new Recttest();
            r.Testfun();
            Console.WriteLine("test=" + r.test);
            Console.ReadKey();

        }
    }
}