Why abstract classes necessary?

Posted by bala3569 on Stack Overflow See other posts from Stack Overflow or by bala3569
Published on 2010-04-26T12:15:43Z Indexed on 2010/04/26 12:23 UTC
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c#

1.What is the point of creating a class that can't be instantiated?

Most commonly to serve as a base-class or interface (some languages have a separate interface construct, some don't) - it doesn't know the implementation (that is to be provided by the subclasses / implementing classes)

2.Why would anybody want such a class?

For abstraction and re-use

3.What is the situation in which abstract classes become NECESSARY?can anyone brief it with an example?

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