28.整数的二进制表示中1的个数

//20130215

#include <iostream>
using namespace std;
int count1(int n);
int main(int argc, char* argv[])
{
int n = 64;
cout<<count1(n);
return 0;
}
int count1(int n)
{
int c = 0;
while (n != 0)
{
n = n & (n - 1);
c++;
}
return c;
}