Question 20

Code Analysis:

int func(int num) {
    int count = 0;
    while (num) {
        count++;
        num >>= 1;
    }
    return (count);
}

In each iteration, count increases by 1 and num is right-shifted by 1 bit (num >>= 1), discarding its least significant bit. The loop terminates when num becomes 0.
Hence, the function computes the position of the most significant 1-bit, which is $\lfloor \log_2(\text{num}) \rfloor + 1$ (the total number of bits in the binary representation of num).

Evaluate for $num = 435$:

• Find powers of 2 enclosing 435:
  $$2^8 = 256 \le 435 < 512 = 2^9.$$
• In binary:
  $$435 = 256 + 128 + 32 + 16 + 2 + 1 = 110110011_2.$$
• The binary string $110110011_2$ has exactly $9$ bits.
• After 9 right-shift operations, num becomes 0.

Therefore, func(435) returns 9.