如何在Java中逐位读取整数？

Question

我想取一个int作为输入,并返回第k位.

int getBit(int n, int k){
    return kth bit in n;
}

我该怎么办？

Answer 1

使用按位运算符:

int getBit(int n, int k) {
    return (n >> k) & 1;
}

说明(以位为单位):

n
100010101011101010 (example)
n >> 5
000001000101010111 (all bits are moved over 5 spots, therefore
&                   the bit you want is at the end)
000000000000000001 (0 means it will always be 0,
=                   1 means that it will keep the old value)
1

Answer 2

return (n >> k) & 1;

在这里,n >> k将k-th位移到最不重要的位置,并& 1屏蔽掉其他所有内容.

Answer 3

如果最低有效位是位数0：

return (n>>k)&1;