Optional in C#

CoolKidsClass.cs

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

namespace OptionalParams
{
    public class CoolKidsClass
    {
        List<int> numbers = new List<int>();
        public string text = "";
        public CoolKidsClass(string _text)
        {
            text = _text;
            for (int i = 0; i < 100; i++)
            {
                numbers.Add(i);
            }
        }
    }
}

output.txt

instantiated in StaticMethod
instantiated in Main

Program.cs

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

namespace OptionalParams
{
    class Program
    {
        static void Main(string[] args)
        {
            StaticMethod();
            StaticMethod(new CoolKidsClass("instantiated in Main"));
            Console.ReadKey();
        }

        public static void StaticMethod(CoolKidsClass ckc = null)
        {
            if (ckc == null) ckc = new CoolKidsClass("instantiated in StaticMethod");

            Console.WriteLine(ckc.text);
        }
    }
}