Chodadog... the isset() function checks to see if the variable has been set (if it has a value). if so, it gives a result of TRUE.
the code i posted checks to see if W has been given a value, and if not, it gives W a value of 99999 or whatever else you want.
i posted it in one line, but it could be broken into several lines
PHP Code:
<?php
if (!isset($w)) {
$w = 999999;
}
?>
the empty() function does more or less the same thing... except that if W = 0, isset() will return TRUE but empty() will return FALSE