[PHP] When are Form Variables Null?

Hi, I've been wondering the behavior of browsers and POST submissions.. basically I'd like to know the behavior of: is_null(), empty(), and isset(). I've found that sometimes when an item is not filled out, the variable is still set on the subsequent page, like $_POST['var'] = ; What does

Re: [PHP] When are Form Variables Null?

Al, This depends entirely on your browser actually, as it is the one sending form variables back to the server in a POST request. Luckily, browsers are very consistent with how they handle this. :) Off the top of my head (I might be forgetting some form field types): text fields - always set