PHP | 位操作符

作者 886

位操作符

位操作符用于对操作数执行位级操作。首先将运算符转换为位级，然后对操作数进行计算。数学运算，如加法、减法、乘法等，可以在位级进行，处理速度更快。在PHP中，在位级工作的运算符是:

  • &(位和):这是一个二进制运算符，也就是说，它在两个操作数上工作。在PHP中，位和运算符接受两个数字作为操作数，并对两个数字的每一个位执行操作。只有当两个比特都是1时，AND的结果才为1。
    语法

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

    例子
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    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):这也是二进制运算符，即工作在两个操作数。位操作符将两个数字作为操作数，并对两个数字的每一个位执行或操作。OR的结果是1两个比特中的任何一个都是1。
    语法

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

    例子
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    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.)

     
  • ^(位XOR):这也是二元运算符即作用于两个操作数。这也称为独占或操作符。按位XOR将两个数字作为操作数，并对两个数字的每一位执行XOR操作。如果两个比特不同，XOR的结果是1。
    语法

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    $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
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    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.)

     
  • ~(位不):这是一个一元运算符，也就是说只对一个操作数工作。位非运算符取一个数字并对它的所有位进行逆运算。
    语法
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    ~$number
     
    This will invert all the bits of $number.

    例子
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    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):这是一个二进制运算符，也就是对两个操作数进行操作。位左移位运算符取两个数字，左移位第一个操作数的位，第二个操作数决定移位的位置数。
    语法

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    $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
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    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1位等于乘以2。
  • >>(按位右移):这也是一个二进制运算符，也就是对两个操作数进行操作。位向右移位运算符取两个数字，右移位第一个操作数的位，第二个操作数决定移位的位置数。
    语法

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    $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
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    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:按位右移1位等于按2除。

下面是PHP中逐位运算符的实现:

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<?php
// PHP code to demonstrate Bitwise Operator.
// Bitwise AND
$First = 5;
$second = 3;
$answer = $First & $second;
print_r("Bitwise & of 5 and 3 is $answer");
print_r("\n");
// Bitwise OR
$answer = $First | $second;
print_r("Bitwise | of 5 and 3 is $answer");
print_r("\n");
// Bitwise XOR
$answer = $First ^ $second;
print_r("Bitwise ^ of 5 and 3 is $answer");
print_r("\n");
// Bitwise NOT
$answer = ~$First;
print_r("Bitwise ~ of 5 is $answer");
print_r("\n");
// Bitwise Left shift
$second = 1;
$answer = $First << $second;
print_r("5 << 1 will be $answer");
print_r("\n");
// Bitwise Right shift
$answer = $First >> $second;
print_r("5 >> 1 will be $answer");
print_r("\n");
?>

输出

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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

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