Logical Operators

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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 $f before the "or" operation occurs// Acts like: (($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 $h before the "and" operation occurs// Acts like: (($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)