PHP |位运算符

位运算符用于对操作数执行位级操作。运算符首先转换为位级，然后对操作数进行计算。诸如加法、减法、乘法等数学运算可以在位级别执行以加快处理速度。在PHP中，位级别的运算符有：

&（按位与）：这是一个二元运算符，即它适用于两个操作数。 PHP中的位与运算符将两个数字作为操作数，并对两个数字的每一位进行与运算。仅当两个位都为 1 时，AND 的结果才为 1。

语法：

$First & $Second

This will return another number whose bits are 
set if both the bit of first and second are set.

例子：

Input: $First = 5,  $Second = 3

Output: The bitwise & of both these value will be 1. 

Explanation:
Binary representation of 5 is 0101 and 3 is 0011. 
Therefore their bitwise & will be 0001 (i.e. set 
if both first and second have their bit set.)

| （按位或）：这也是二元运算符，即适用于两个操作数。按位或运算符将两个数字作为操作数，并对两个数字的每一位进行 OR。 OR 的结果为 1 两位中的任何一位为 1。

语法：

$First | $Second

This will return another number whose bits are 
set if either the bit of first or second are set.

例子：

Input: First = 5, Second = 3

Output: The bitwise | of both these value will be 7. 

Explanation:
Binary representation of 5 is 0101 and 3 is 0011.
Therefore their bitwise | will be 0111 (i.e. set 
if either first or second have their bit set.)

^（按位异或）：这也是二元运算符，即适用于两个操作数。这也称为异或运算符。按位异或将两个数字作为操作数，并对两个数字的每一位进行异或。如果两个位不同，则异或的结果为 1。

语法：

$First ^ $Second

This will return another number whose bits are 
set if one of the bit in first or second is 
set but not both.

例子：

Input: First = 5, Second = 3 

Output: The bitwise ^ of both these value will be 6. 

Explanation:
Binary representation of 5 is 0101 and 3 is 0011. 
Therefore their bitwise ^ will be 0110 (i.e. set 
if either first or second have their bit set but 
not both.)

~ (Bitwise NOT) : 这是一个一元运算运算符，即只对一个操作数起作用。按位非运算符取一个数字并将其所有位取反。

语法：

~$number

This will invert all the bits of $number.

例子：

Input: number = 5

Output: The bitwise '~' of this number will be -6.

Explanation:
Binary representation of 5 is 0101. Therefore the
bitwise ~ of this will be 1010 (inverts all the 
bits of the input number)

<<（按位左移）：这是一个二元运算符，即适用于两个操作数。按位左移运算符取两个数字，左移第一个操作数的位，第二个操作数决定要移位的位数。

语法：

$First << $Second

This will shift the bits of $First towards the 
left. $Second decides the number of time the
bits will be shifted.

例子：

Input: First = 5, Second = 1

Output: The bitwise << of both these value will be 10. 

Explanation:
Binary representation of 5 is 0101 . Therefore, 
bitwise << will shift the bits of 5 one times 
towards the left (i.e. 01010 )

注意：按位左移一位等价于乘以 2。

>>（按位右移）：这也是二元运算符，即适用于两个操作数。按位右移运算符取两个数字，右移第一个操作数的位，第二个操作数决定要移位的位数。

语法：

$First >> $Second

This will shift the bits of $First towards the 
right. $Second decides the number of time the 
bits will be shifted.

例子：

Input: First = 5, Second = 1 

Output: The bitwise >> of both these value will be 2. 

Explanation:
Binary representation of 5 is 0101 . Therefore, 
bitwise >> will shift the bits of 5 one times 
towards the right(i.e. 010)

注意：按位右移一位相当于除以 2。

下面是PHP中按位运算符的实现：

> $second;
    print_r("5 >> 1 will be $answer");
      
    print_r("\n");
?>

输出：

Bitwise & of 5 and 3 is 1
Bitwise | of 5 and 3 is 7
Bitwise ^ of 5 and 3 is 6
Bitwise ~ of 5 is -6
5 << 1 will be 10
5 >> 1 will be 2