Advantage of abstract class over interface

Advantage of abstract class over interface:

Consider versioning:

·         You cannot add members to interface without breaking the existing code.  

·         But you can safely add new members to abstract classes.

http://stackoverflow.com/questions/9143106/advantage-of-abstract-class-over-interface

Choosing between interface & abstract class:

·         Use interface when you want to implement multiple inheritance.

·         Use interface for decoupling

·         Use abstract class in case of frequent versioning scenario.

http://msdn.microsoft.com/en-us/library/ms229013.aspx