What is the difference between virtual and non-virtual destructor?
PICTURE THIS: 1, 2, 2, 8
Simple meaning
Deleting a derived object through a base pointer needs a virtual destructor or you get UB.
WHY — OOP instead of guessing?
Why interviewers care about OOP:
contrast on OOP, not two memorised paragraphs.
the developer, then one case where picking wrong hurts.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Deleting a derived object
through a base pointer needs a virtual destructor or you get UB.
- 2Value semantics stacks do
not need it.
- 3Interfaces meant for polymorphism
should have virtual destructors.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Deleting a derived object through a base pointer needs a virtual destructor or you get UB. Value semantics stacks do not need it.