static void Main(string[] args) { //var a = new AbstractClass(); NG var b = new DerivedClass(); b.sayHi(); b.saySomething(); var c = (AbstractClass)b; c.sayHi(); c.saySomething(); //var s = new StaticClass(); NG var l = new SealedClass(); l.SayHello(); l.SayHi(); Console.ReadKey(); }
public static void SayHi(this SealedClass cc) { Console.WriteLine("HI"); }