when to use abstract class and when to use interface in c# [duplicate]

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interface and abstract class.

Abstract classes vs Interfaces

Can anyone tell me when one should use an abstract class and when one should use an inte开发者_Python百科rface with sample scenarios?

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If you're defining behavior (like IEnumerable, since a List acts like an IEnumerable), then use an interface, but if you're defining a kind of object (an IS-A) relationship, use an abstract class (like Stream -- since a MemoryStream IS-A Stream).

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You should use an abstract class if you need to supply a base implementation.

Otherwise, use an interface.

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When you want to provide an implementation of a method/set of methods but don't want people to directly instantiate your parent class, use an Abstract Class.

If you want to define what members a class must interface, but not provide any implementation, use an Interface.