using System;

public class Program

{

    public static void Main()

    {

        StructX? sx = default(StructX);

        Console.WriteLine( sx is {});

        Console.WriteLine( sx is null);

        sx = new StructX();

        Console.WriteLine( sx is {});

        ClassX cx = default(ClassX);

        Console.WriteLine( cx is {});

        Console.WriteLine( cx is null);

        cx = new ClassX();

        Console.WriteLine( cx is {});

    }

}

​

public struct StructX {}

​

public class ClassX {}

​