《Cracking the Coding Inteview》——第5章：位操作——题目5

 1 // 5.5 Determine the number of bits required to convert integer A to B.
 2 #include <cstdio>
 3 using namespace std;
 4 
 5 int numberOfOnes(unsigned int n)
 6 {
 7     int res = 0;
 8     
 9     while (n != 0) {
10         n = n & (n - 1);
11         ++res;
12     }
13     
14     return res;
15 }
16 
17 int main()
18 {
19     unsigned int a, b;
20     
21     while (scanf("%u%u", &a, &b) == 2) {
22         printf("%d\n", numberOfOnes(a ^ b));
23     }
24     
25     return 0;
26 }