Well; call me 1980's! I didn't know this. PHP5's built in filter functions introduced in 5.2.

Because our company has to comply to PCI standards this means some pretty strict sanitization of user input variables, generally good coding practice. To date I've been using a custom written sanitization function but earlier today I was reading an article about something completely different and came across the humble filter_var_array(); function and all of PHP5's new pre-defined constants (FILTER_VALIDATE_EMAIL, FILTER_VALIDATE_IP, FILTER_SANITIZE_STRING to name just a few!).