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");
}