Converting piped data to values from html to phpcgi

I am using php as a cgi. The data from my html is piped through stdin using this code: <? $fp=popen("cat","r"); $str=fgets($fp); print $str; ?> The result I am getting looks like this: (which is correct) sender_name=zedleon&sender_email=support@passeycorp.com&sender_msg=This+is+a +test&Submit=Submit What I need to do now is to convert the piped string into the individual values $sender_name, $sender_email, $sender_msg. Does anybody know a way to do this...any help is appreciated.