Swapping two integer values without using temporary variables in php

echo '

';
echo 'X:

';
echo 'Y:

';
echo '

';
echo '

';

$x = $_POST['x'];
$y = $_POST['y'];

function swap(&$x,&$y){
$x ^= $y ^= $x ^= $y;
}

swap($x,$y);

print "X = " .$x. "

";
print "Y = " .$y. "";


?>