C/C++位运算

0 & 0 = 0
1 & 0 = 0
0 & 1 = 0
1 & 1 = 1

0 | 0 = 0
0 | 1 = 1
1 | 0 = 1
1 | 1 = 1

1 ^ 1 = 0
0 ^ 0 = 0
1 ^ 0 = 1
0 ^ 1 = 1

00001010 << 2 = 00101000 每一位左移两位，右边多余出来的部分补0
11000101 << 2 = 00010100

10101001 >> 2 = 00101010 每一位右移两位， 左边多余的部分补0
11110000 >> 3 = 00011110

21 = (00010101)
21 >> 1 = (00001010) = 10 相当于 21/2
21 << 1 = (00101010) = 42 相当于 21*2 

int count = 0;
while(number){
  count = count++;
  number = number & (number-1) // 该运算使number右边的第一个1置0
}