For example we wanted to swap two variable values given
$x = 10;
$y = 20;
The usual way of exchanging their variables is to use a temporary variable like the one below
$x = 10;
$y = 20;
$z = $x; // $z will be equal to 10 now which will serve as a temporary variable
$x = y; // $x will be equal to 20 now
$y = $z; // $y will be 10 now
Their is another way to do this without using temporary variable is the use of list() function
$x = 10;
$y = 20;
list($x, $y) = array($y, $x);
You can also do this in multiple variables
$sDog1 = "Boston Terrier";
$sDog2 = "American Bulldog";
$sDog3 = "German Shepperd";
$sDog4 = "Great Dane";
list($sDog1, $sDog2, $sDog3, $sDog4) = array($sDog3, $sDog1, $sDog4, $sDog2);