PHP Operator (4) 'Bit Operator' Example Explanation

We have already explained the "php arithmetic operator", "php string operator", and "Assignment operator" in PHP operators. , today I will give you a detailed introduction to the "bit operators" in PHP operators.

Bit operators are not often used in PHP, but they are still very useful. In the following content, we will give examples to illustrate the usage of bit operators.

The bit operator refers to the operation after aligning the binary bits from the low bit to the high bit. It allows the evaluation and operation of the specified bits in the integer number.

The operators in PHP are as shown in the following table

Let’s use examples to describe the operators in the above table

<?php

$m=1;                //1=0 00000001
$n=2;                 //2=00000010

$mn=$m&$n;
echo $mn."<br/>";

$mn=$m^$n;
echo $mn."<br/>";

$mn=$m|$n;
echo $mn;

?>

Code running results:

Example explanation :

$m&$n : 1 when both are 1, otherwise 0. That is, set the bits in $a and $b that are both 1 to 1, otherwise set to 0.

00000001 ← $m
& 00000010 ← $b

The comparison result is 00000000, so the output is 0

$m^$ n: In the process of bitwise OR, the difference is 1 and the same is 0.
00000001 ← $m

^ 00000010 ← $n

So the result is 00000011, and 3 is output.

$m|$n: In the process of bitwise OR, 1 is 1, all 0 is 0,

00000001 ← $m

| 00000010 ← $n

The result is 00000011, so the output is 3

The above example talks about "bitwise OR", "bitwise OR", "bitwise XOR", let's take a look at the next three examples

Bitwise NOT or bitwise negation example, the code is as follows

<?php
$m = 2;
$m1 = ~$m;
echo $m1;
?>

Running results

At this time our running result is -3, we need to pay attention here.

Note: In computers, negative numbers are expressed in the complement form of their positive values.

1: The 32-bit original code of 2 is 0000 0000 0000 0000 0000 0000 0000 0010

2: The bitwise inversion is 1111 1111 1111 1111 1111 1111 1111 1101

Since the first number is 1 and the sign bit is 1, it is a negative number. Therefore, the complement form of its positive value is expressed as: (the sign bit remains unchanged, bitwise inversion, and 1 is added at the end)

1000 0000 0000 0000 0000 0000 0000 0011

So the output is -3

Left shift right shift code example

<?php
$m = 12;     // 12=00001100
$n = 3;     // 3=00000011

$mn= $m << $n;
echo $mn ."<br/>";

$mn= $m >> $n;
echo $mn ; 
?>

Running results:

Example explanation:

$m: Move the bits in $m to the left $n times (each move means "multiply by 2", that is, "multiply by 2$b").
0000 1100 ← $m

$m>>$n: Move the bits in $m to the right $n times (each move means "divide by 2", that is, "multiply by 2 -$b "). 0000 1100 ← $m

in PHP operations.

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