im not talking about simple base class i am talking about abstract class the main goal of abstarct class is to let inherited classes implement all or at least one of its abstarct methods. it is an option not a force; base class is somthing and abstract class as a base for childs is another story.

about c# i mentioned that you come here and make me correct if i am wrong bacuse i don't think there is any way to implemet an abstract method in abstract class. in comparsion between languages learn us something new.