Code for blog entry: "Interview Question Pitfalls"

count_bits.c

long count_bits(long number) {
    // Accumulates the total bits set in `number`
    unsigned int count;

    // This loop initializes the count, loops only until all bits have been cleared and
    // increments the count each time through the loop.
    for (count = 0; number; count++) {
        // Clear the least significant bit set
        number &= number - 1;
    }

    return count;
}