Can abstract classes can be instanciated?

Abstact Class is nothing but a true virtual class..
This class cannot be instantiated instead it has to be inherited.
The method in abstract class are virtual and hence they can be overriden in the child class. (More...)

1) Rectangle
2) Ellipse
3) Line
4) Polyline
5) Polygon
6) Path (More...)

a class may inherit several interfaces, a class may inherit only one abstract class (More...)

Unlimited (More...)

Queue, Stack, BitArray, HashTable, LinkedList, ArrayList, Name ValueCollection, Array, SortedList, HybridDictionary, ListDictionary, StringCollection, StringDictionary (More...)

The .NET Framework provides specialized classes for data storage
and retrieval.
These classes provide support for stacks, queues, lists, and hash tables. (More...)

An Abstract class is a class with some common/certain implementations and defines abstraction for other services which are implemented in its concrete sub classes, whereas interface only have method declaration with zero implementations. An abstract class and Interface both have method only but not have body of method. The difference between Abstract class and An Interface is that if u call Abstract class then u have to call all method of that particular Abstract class but if u call an Interface then it is not necessary that u call all method of that particular interface. An abstract class is a special kind of class that cannot be instantiated. So the question is why we need a class that cannot be instantiated? An abstract class is only to be sub-classed (inherited from). In other words, it only allows other classes to inherit from it but cannot be instantiated. The advantage is that it enforces certain hierarchies for all the subclasses. In simple words, it is a kind of contract that forces all the subclasses to carry on the same hierarchies or standards.

An interface is not a class. It is an entity that is defined by the word Interface. An interface has no implementation; it only has the signature or in other words, just the definition of the methods without the body. As one of the similarities to Abstract class, it is a contract that is used to define hierarchies for all subclasses or it defines specific set of methods and their arguments. The main difference between them is that a class can implement more than one interface but can only inherit from one abstract class. Since C# doesn't support multiple inheritance, interfaces are used to implement multiple inheritance.


Shashi Ray (More...)

No. About the closest you can come is using the internal keyword, which allows access within the current assembly. But, there is no way to specify specific a class that knows about another class's private implementation. (More...)

Unlimited (More...)

Unlimited (More...)