Differences between Abstract Classes and Interfaces in C#

Abstract classes and interfaces are important concepts in C# that provide different ways of defining and implementing classes. Understanding the differences between them is crucial for .Net developers. Here are some key distinctions:

• Definition: An abstract class can have both abstract and non-abstract members, while an interface can only have method signatures and properties.
• Implementation: Abstract classes can provide partial implementation of methods, while interfaces cannot contain implementation details and only define method signatures.
• Inheritance: A class can only inherit from one abstract class, but it can implement multiple interfaces.
• Access Modifiers: Abstract class members can have different access modifiers, while interface members are public by default.
• Multiple Inheritance: C# does not support multiple inheritance with abstract classes but allows a class to implement multiple interfaces.

When designing a class hierarchy in C#, choosing between an abstract class and an interface depends on the specific requirements of the application. Abstract classes are useful when defining a common base implementation, while interfaces are helpful for defining contracts that multiple classes can fulfill.