Is $a an interger?

Hi folks, this probably qualifies as a dumb newbie question. I want to use PHP to make sure a value submitted in a form is an integer, if not I want to prompt the user to change that value. However I have discovered that no matter what I do PHP thinks values submitted from the form are strings. I tired using settype() but that changes the value to 0, and when the form is resubmitted the type changes again to string. My brilliant (but non functional code) is\ $type=gettype($var1); if ($type=="integer") ... } else { if ($type="string") { settype($var1, "integer") ...//stuff to show form again } } What do I need to do to make PHP think the values submitted by the form are integers Thanks,