PHP About bitwise operators

Common four bit Operators:& (bitwise AND), | (bitwise OR), ^ (bitwise XOR), ~ (bitwise inverse)

& (Bitwise AND): The corresponding bit is 1 o'clock at the same time, 1 after the & operation, otherwise 0

| (bitwise OR): one of the corresponding bits is 1 o'clock, and after the | operation is 1, and 0 is 0

^ (Bitwise XOR): The corresponding bit is 1 o'clock, the ^ operation is 1, at the same time 0 is 0, and the 1 o'clock ^ operation is also 0

~ (bitwise Reversed): $a + (~ $a) =-1

In a computer, negative numbers are expressed in the form of a positive complement.
Here we need to know three concepts, original code, anti-code and complement.

The original code: an integer, converted into a binary number according to the absolute size, called the original code.

8 The original code is: 0000 0000 0000 0000 0000 0000 0000 1000

Inverse code: The binary number is reversed, the resulting new binary number is called the original binary number of the inverse code. The reverse operation means: 1 change 0, 0 to 1.

8 bitwise inversion: 1111 1111 1111 1111 1111 1111 1111 0111

Complement: The inverse code plus 1 is called the complement. That is, to get a number of the complement, first get the anti-code, and then add the inverse code 1, the resulting number is called the complement.

The complement of a positive number is the same as its original code; the complement of a negative number is the minus 1 of its inverse code.

Anti-code plus 1:1000 0000 0000 0000 0000 0000 000 1001; This will get a positive complement of negative numbers. That's--9.

Reference: http://www.cnblogs.com/setsail/archive/2013/05/22/3093542.html

http://my.oschina.net/WarRome/blog/90707

The above explanation oneself also did not see too understand, but practice obtains $a+ (~ $a) =-1

Here are a few examples:

$m = 8;
$n = 12;
$p =-109;
$mn = $m & $n;
echo $mn. "
";
$mn = $m | $n;
echo $mn. "
";
$mn = $m ^ $n;
echo $mn. "
";
$mn =~ $m;
echo $mn. "
";
$mn =~ $p;
echo $mn. "
";
?>

Output Result:

8
12
4
-9
108

On the issue of bitwise inversion, and then pondering

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