.NET Fiddle

gistfile1.txt

class Person
{
	public Person(string name = "Joe Somebody")
	{
		Name = name;
	}

	public string Name { get; private set; }

	public string Greet()
	{
		if (Name == null)
			return "Hello, stranger!";

		return string.Format("Hello, {0}!", Name);
	}
}

Console.WriteLine(new Person().Greet());