bit_count.c

#include <stdio.h>

int bit_count(int n);

int main()
{
	int i, limit = 255;

	for (i = 0; i <= limit; i++)
	{
		printf("Input: %d\tBit Count: %d\n", i, bit_count(i));
	}

	return 0;
}

int bit_count(int n)
{
	int count = 0;

	while (n)
	{
		count += n % 2;	// If we've got an odd number, add 1
		n /= 2;		// Divide by 2, rounding down
	}

	return count;
}