abstract classes vs interfaces

Big problem ... I have a test tomorrow about Polymorphism, inheritance, interfaces and abstract classes in C#.


My main question is... abstract classes and interfaces seem to do the same thing ? (Or am i missing something ?)

Then when do you use a abstract class and when do you prefer an interface instead ?



Thanks in advance

Off the top of my head ,
classes can inherit one class but many interfaces .So, using interfaces would give you multiple inheritance .

abstract classes :
1- usually used as base classes
2-can't be instantiated.

thank you very much ! that's a great answer, my compliments

You should check MSDN for more info .It's helpful with examples.
good luck in your test.;)

thanks :)
I've put up another post about another question. Who knows , you might be able to help there too ? :D would be great :bigyello: