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## Logical Operators

Logical Operators
Example | Name | Result
--- | --- | ---
$a and $b | And | `TRUE` if both $a and $b are `TRUE`.
$a or $b | Or | `TRUE` if either $a or $b is `TRUE`.
$a xor $b | Xor | `TRUE` if either $a or $b is `TRUE`, but not both.
! $a | Not | `TRUE` if $a is not `TRUE`.
$a && $b | And | `TRUE` if both $a and $b are `TRUE`.
$a || $b | Or | `TRUE` if either $a or $b is `TRUE`.

The reason for the two different variations of "and" and "or" operators is that they operate at different precedences. (See Operator Precedence.)

Example #1 Logical operators illustrated

`<?php
// --------------------
// foo() will never get called as those operators are short-circuit
$a = (false && foo());
$b = (true || foo());
$c = (false and foo());
$d = (true or foo());
// --------------------
// "||" has a greater precedence than "or"
// The result of the expression (false || true) is assigned to $e
// Acts like: ($e = (false || true))
$e = false || true;
// The constant false is assigned to $f and then true is ignored
// Acts like: (($f = false) or true)
$f = false or true;
var_dump($e, $f);
// --------------------
// "&&" has a greater precedence than "and"
// The result of the expression (true && false) is assigned to $g
// Acts like: ($g = (true && false))
$g = true && false;
// The constant true is assigned to $h and then false is ignored
// Acts like: (($h = true) and false)
$h = true and false;
var_dump($g, $h);
?>`

The above example will output something similar to:

    bool(true)
    bool(false)
    bool(false)
    bool(true)

Incrementing/Decrementing Operators
String Operators
Operators
PHP Manual