search criteria in LDAP

Hi,

Could anyone help me with my codes
In fact i want to use several search criteria that i got from a form. If the user fills one or some of the fields, the search will B done using the fields that have been filled. I've tried to do it with at least 2 fields but i think that i'm stuck
here is my code:

$filter1="cn=$prenom";
$filter2="sn=$nom";
$filter3="codediplomecodeetudiant=$diplome";
$filter4="ue=$enseignement";
$filter=(&&($filter1)($filter2));

//precise the attributs we want
$justthese = array("sn","cn","codediplomecodeetudiant","ue");

//do the search
$recherche=ldap_search($ldapconn,$dn,$filter,$just these);

thanks in advance
eva

strzalka55@yahoo.fr