C#第一个helloworld程序

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

namespace helloworld
{
    class HelloWorld
    {
        public static void Main()
        {
            Console.WriteLine("This is My First C# Program Hello World!");
            MessageBox.Show("Hello World!");
            Console.ReadLine();
        }
    }
}