Difference between Abstract Class and Interface in C#

Posted by jineesh uvantavida on Monday, June 7, 2021

Abstract Class

Its a way to achieve abstraction in c#.
Not instantiated directly
must contain at least one abstract method.
used to define base class.
contains both declaration and definition.
contains constructor.
it can contain static members
contains different types of access modifiers like public, private, protected.
performance of abstract class is fast.
used to implement core identity of class
a class can only use one abstract class.
if many implementation are same kind and common behavior, then it is superior to use abstract class.
it can be fully, partially or not implemented.

Interface

can have methods, properties, events and indexers as its members
only declaration of the members.
implementation of interface member is done by the class who implements the interface.
multiple inheritance is achieved by interface.
it does not contain constructor
it does not contain static members
contains only public access modifier because everything in the interface is public
performance is slow because it requires time to search actual method in the corresponding class
used to implement peripheral abilities of class
a class can have multiple interface.
if many implementation share only methods, then it is superior to use interface
it should be fully implemented

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