hello world c#

// Hello World! program
namespace HelloWorld
{
    class Hello {         
        static void Main(string[] args)
        {
            System.Console.WriteLine("Hello World!");
        }
    }
}

Console.WriteLine("Hello World!");

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello, world!");

            // To prevents the screen from  
            // running and closing quickly 
            Console.ReadLine();
        }
    }
}