PHP Bitwise Operators « ByREV

Operator	Description	Result
$a & $b	And	Bits that are set in both $a and $b are set.
$a | $b	Or (inclusive or)	Bits that are set in either $a or $b are set.
$a ^ $b	Xor (exclusive or)	Bits that are set in $a or $b but not both are set.
$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”)
~ $a	Not	Bits that are set in $a are not set, and vice versa.

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Bitwise operators allow evaluation and manipulation of specific bits within an integer. If both the left-hand and right-hand parameters are strings, the bitwise operator will operate on the characters’ ASCII values.

Warning: 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 bit. Use functions from the gmp extension ( gmp_and(), gmp_or(), gmp_xor(), gmp_testbit(), gmp_clrbit() ) for bitwise manipulation on numbers beyond PHP_INT_MAX.