PHP Manual

Bitwise Operators

Bitwise operators allow you to turn specific bits within an integer on or off. If both the left- and right-hand parameters are strings, the bitwise operator will operate on the characters' ASCII values.

echo 12 9// Outputs '5'

echo "12" "9"// Outputs the Backspace character (ascii 8)
                 // ('1' (ascii 49)) ^ ('9' (ascii 57)) = #8

echo "hallo" "hello"// Outputs the ascii values #0 #4 #0 #0 #0
                        // 'a' ^ 'e' = #4

echo "3"// Outputs 1
              // 2 ^ ((int)"3") == 1

echo "2" 3// Outputs 1
              // ((int)"2") ^ 3 == 1

Bitwise Operators
Example Name Result
$a & $b And Bits that are set in both $a and $b are set.
$a | $b Or Bits that are set in either $a or $b are set.
$a ^ $b Xor Bits that are set in $a or $b but not both are set.
~ $a Not Bits that are set in $a are not set, and vice versa.
$a << $b Shift left Shift the bits of $a $b steps to the left (each step means "multiply by two")
$a >> $b Shift right Shift the bits of $a $b steps to the right (each step means "divide by two")

Don't right shift for more than 32 bits on 32 bits systems. Don't left shift in case it results to number longer than 32 bits.

PHP Manual