位操作，而不是用于复制位图的if

Question

我想避免下面的if语句。我可以只使用逐位运算符将设置的位从旧的位数组复制到新的位数组吗？

#define BYTE_POS(pos) (pos / CHAR_BIT)
#define BIT_POS(pos) (1 << (CHAR_BIT - 1 - (pos % CHAR_BIT)))
if ((old_array[BYTE_POS(old_pos)] & BIT_POS(old_pos)) != 0) {
    new_array[BYTE_POS(new_pos)] |= BIT_POS(new_pos);
}

Answer 1

将BIT_POS更改为：

#define BIT_POS(pos, state) (state << (CHAR_BIT - 1 - (pos % CHAR_BIT)))

然后将代码更改为：

bool state = (old_array[BYTE_POS(old_pos)] & BIT_POS(old_pos, 1)) != 0);
new_array[BYTE_POS(new_pos)] |= BIT_POS(new_pos, state);