What is an abstract class in C++?
PICTURE THIS: OOP PILLARS
Simple meaning
A class with at least one pure virtual function, written as virtual f() = 0.
WHY — OOP instead of guessing?
Why interviewers care about OOP:
who only read docs from people who shipped.
and tied to C++ work.
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:
- 1A class with at
least one pure virtual function, written as virtual f() = 0.
- 2I cannot construct it,
only derive.
- 3It is the C++
interface-plus-optional-code pattern.
- 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
A class with at least one pure virtual function, written as virtual f() = 0. I cannot construct it, only derive.