OOP Interview Questions — a practical guide to OOP interview questions with clear examples you can reuse in real projects.
OOP Tutorial Series (63/65). Prefer one article? Read the complete OOP tutorial.
Short description
Be ready to explain encapsulation, inheritance vs composition, interfaces vs abstract classes, and SOLID with examples.
Sample Q&A
Q: Interface vs abstract class?
A: Interface = contract only (mostly); abstract class can share code.
Q: Overloading vs overriding?
A: Overloading = same name different signatures (limited in PHP); overriding = redefine parent method.
Q: Why DI?
A: Loose coupling + easier testing.
Q: Composition vs inheritance?
A: Prefer has-a composition for flexibility.