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> **Possible Duplicates:**  
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> [interface and abstract class.](https://stackoverflow.com/questions/4607081/interface-and-abstract-class)  
> 
> [Abstract classes vs Interfaces](https://stackoverflow.com/questions/1474249/abstract-classes-vs-interfaces) 
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> 

Can anyone tell me when one should use an abstract class and when one should use an interface with sample scenarios?