Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

Which entities can implement an interface in C#?

1. Only classes

2. Both classes and interfaces

3. Classes and structs

4. Structs only

The correct answer is: Classes and structs

In C#, both classes and structs can implement an interface. When an interface is defined, it specifies a contract that can be implemented by any class or struct that chooses to do so. This allows for a consistent way of interacting with different types of objects that conform to the same interface. Classes are the most common type to implement interfaces, as they offer full feature sets like inheritance and the ability to encapsulate data and behavior. Structs, while typically used to represent simple data types, can also implement interfaces, which lets them take part in polymorphism and interface-based programming. This flexibility is beneficial because it allows for a range of implementations, providing developers with a way to design systems where various types (both classes and structs) can be treated uniformly if they adhere to the same interface. Through this mechanism, a common method can be called on any object that implements the interface, regardless of whether that object is a class or a struct. This promotes code reusability and can lead to cleaner, more maintainable code.