What does the following C function f() return?

int f(unsigned int N) {
  unsigned int counter = 0;
  while (N > 0) {
    counter += N & 1;
    N = N >> 1;
  }
  return counter == 1;
}

1. A1 if N is odd, otherwise 0
2. B1 if N is a power of 2 , otherwise 0
3. C1 if the binary representation of N is all 1 s 's, otherwise 0
4. D1 if the binary representation of N has any 1 's, otherwise 0 F()

Pick an option to check yourself, or open the answer below.

Show answer & explanation

Correct answer: B. 1 if N is a power of 2 , otherwise 0

Explanation

The loop counts the 1 bits of N, and the function returns whether that count is exactly 1 — true exactly when N is a power of 2.