/*author:Star date:2010-08-02*/
#include <stdio.h>
#include <assert.h>

int CntBit(unsigned int n)	//分治思想
{
	n = ((n & 0xaaaaaaaa) >> 1 ) + (n & 0x55555555);
	n = ((n & 0xcccccccc) >> 2 ) + (n & 0x33333333);
	n = ((n & 0xf0f0f0f0) >> 4 ) + (n & 0x0f0f0f0f);
	n = ((n & 0xff00ff00) >> 8 ) + (n & 0x00ff00ff);
	n = ((n & 0xffff0000) >> 16) + (n & 0x0000ffff);
	return n;
}

int main(int argc, char *argv[])
{
	unsigned int N;
	int i, j;
	scanf("%u", &N);
	printf("%u:", N);
	i = CntBit(N);
	assert(i >= 0 && i <= 32);
	for(j = 31; j >= 0; --j)
		printf("%d", N&(1<<j) ? 1 : 0);	
	printf("\nhave %d bit that are \'1\'", i);
	return 0;
}

这里数以的大小范围为例。