Count the number of set bits (1s) in binary representation of an integer public int CountSetBits(int n) { int count = 0; while (n != 0) { count += n & 1; n >>= 1; } return count; } Explanation: Shift through each bit; add 1 to count if least significant bit is set.

Answer: lternative using Brian Kernighan’s algorithm: public int CountSetBits(int n) { int count = 0; while (n != 0) { n &= (n - 1); // Drops the lowest set bit count++; } return count; } Follow on:

What interviewers expect

• A clear definition tied to Coding in C# Coding Interview projects
• Trade-offs (performance, maintainability, security, cost)
• When you would and would not use it in production

Real-world example

In a production C# Coding Interview application, teams apply this when handling user-facing features or integration boundaries. For example, you might use it during a sprint where reliability and observability matter—logging metrics, validating edge cases, and documenting the decision in an ADR so future developers understand why the approach was chosen.

How to explain in the interview

1. Define the concept in one or two sentences.
2. Context — where it fits in C# Coding Interview architecture.
3. Example — a specific project, bug, or performance win.
4. Trade-off — what you gain vs what you sacrifice.

Tip: Practice aloud on Toolliyo mock interview or the Interview Q&A section before your real interview.