Swap two variables value without using third variable in php?

We can swamp two variable with the use of php function 

<?php $a='sagar'; $b='deepak';
list($a,$b) = array($b,$a);
echo $a.'-'.$b; ?>
deepak-sagar


We can swap two variable with the use of XOR method too
<?php
$a='11111'; $b='22222';
$a = $a ^ $b;
$b = $a ^ $b;
$a = $a ^ $b;
echo $a;
echo $b;
?>


 We can swap two variable with the use of our logic too
<?php

$a='11111'; $b='22222'; 

$a = $a + $b; 
$b = $a - $b; 
$a = $a - $b;

?>

anther one is here

$a = $a * $b; 
$b = $a / $b; 
$a = $a / $b;