static void Main(string[] args) { var subject = new Subject(); var observerA = new Observer("Observer A"); var observerB = new Observer("Observer B"); var observerC = new Observer("Observer C"); Console.WriteLine("Intially suppose Subject has already written total " + subject.Articles + " article"); Console.WriteLine("\n*******************************************************************************\n"); Console.WriteLine("Registering observers A and B for future articles..............."); subject.registerObserver(observerA); subject.registerObserver(observerB); Console.WriteLine("New article published by Subject,so now observers A and B will be notified....\n"); subject.Articles++; Console.WriteLine("---------------------------------------------------------------------------\n"); Console.WriteLine("Registering observer C for future articles and unregistering observer B from the future articles..............."); subject.registerObserver(observerC); subject.unregisterObserver(observerB); Console.WriteLine("New article published by Subject,so now observers A and C will be notified....\n"); subject.Articles++; Console.WriteLine("\n*******************************************************************************\n"); Console.WriteLine("Finally Subject has written total " + subject.Articles + " article\n"); }