why doesn't default values for this function work - resending because of bad formatting

Hi, I'm having problem with a function that I'll use to validate user input before passing it to MySQL. For strings, I want to make sure that they aren't to long, so I have written this function: function secure_string($unsafe_string, $max_length = -1, $errormessage = "Too many characters." ) { // verify that string isn't longer then $max_length, if $max_length is set if ($max_length > -1) { if (!is_int($max_length)) { error("Variable max_length is not an integer." ); } if (strlen($unsafe_string) > $max_length) { error($errormessage); } } [... and the validation will continue here.] When I want to use the max length check I pass a value to the function like this: $a_header = secure_string($_POST['a_header'], 60, "Header must not be more then 60 characters." ); But I having to problems: 1) If no max length is passed, and $max_length gets the value -1, the if- loop if ($max_length > -1) is still run. 2) Calls to my own function error doesn't work. Instead of creating a popupwindow with javascript (which works in other places where error() is called) the errormessage is printed like html. What's wrong? Best regards, -- anders thoresson