.NET Core SDK

cmd

dotnet —version
dotnet new console —name HelloCharp

using System;
using System.IO;
namespace HelloCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            var stream = File.Create(@"C:\Users\Administrator\Desktop\Playgroud\HelloCSharp\Test.txt");
var writer = new StreamWriter(stream);
writer.WriteLine("Hello C# World");
writer.Flush();
writer.Close();
            Console.WriteLine("Done");
        }
    }
}

Visual Studio Code

using System;
using System.IO;
namespace HelloCSharp
{
    class Program
    {
        static void Main(string[] args)
        {
            var stream = File.Create(@"C:\Users\Administrator\Desktop\Playgroud\HelloCSharp\Test.txt");
            var writer = new StreamWriter(stream);
            writer.WriteLine("HelloC#");
            writer.Flush();
            writer.Close();
            Console.WriteLine("Done");
        }
    }
}