What does the params keyword do?
PICTURE THIS: ARRAY IN MEMORY
Index starts at 0. Scan once for max — O(n).
Simple meaning
It lets a method accept a variable number of arguments as an array.
WHY — C# instead of guessing?
Why interviewers care about C#:
who only read docs from people who shipped.
and tied to .NET 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:
- 1It lets a method
accept a variable number of arguments as an array.
- 2Callers can pass a
comma list without allocating an array themselves.
- 3I avoid params on
hot paths that allocate every call.
- 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
It lets a method accept a variable number of arguments as an array. Callers can pass a comma list without allocating an array themselves.