Ok. Thanks for the reply.
Just to make things a little clearer, I'll copy out an example script straight from the book which uses this strange line. Here goes...
<html>
<head>
<title>Listing 4.1 Testing the type of a variable</title>
</head>
<body?
<?php
$testing; //declares a variable without assigning a value
print gettype ( $testing ); //null
print "<br>";
$testing = 5;
print gettype ( $testing ); //integer
print ("<br>");
$testing = 5.0;
print gettype ( testing ); //double
print ("<br>");
$testing = true;
print gettype ( $testing ); //boolean
print "<br>";
?>
</body>
</html>
