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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" 
 $e  =  false  ||  true ;  // $e will be assigned to (false || true) which is true 
 $f  =  false  or  true ;  // $f will be assigned to false 
 var_dump ( $e ,  $f ); 
 
 // "&&" has a greater precedence than "and" 
 $g  =  true  &&  false ;  // $g will be assigned to (true && false) which is false 
 $h  =  true  and  false ;  // $h will be assigned to true 
 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

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