How do you use RAII for file handles?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
Wrap fopen or OS handles in a class or unique_ptr with a custom deleter.
WHY — Errors instead of guessing?
Why interviewers care about Errors:
question about Errors.
trade-offs, and what you would actually do on a C++ project - not buzzwords.
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:
- 1Wrap fopen or OS
handles in a class or unique_ptr with a custom deleter.
- 2Why it exists
Destructor closes even on exceptions.
- 3Raw fclose paths get
skipped on early returns.
- 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
Wrap fopen or OS handles in a class or unique_ptr with a custom deleter. Destructor closes even on exceptions.