Please help!! how to compare an array with another

Shu! I am currently working on a site where I want to randomly show pictures. I am using sessions to save the id's of the pictures that a user has seen during his/hers visit. My first question is: Can I use an array as a session variable? like this: $arr = array(1, 2, 3, 4, 5); session_start(); session_register("arr"); This array is to be passed on as an argument to a function used to find a random id, that has not yet been seen. This array should be compared to another array with the picture id's. There is two functions to accomplish the following: Create a randomized array consisting of all the pictures id. Find one id in that randomized array that does not exist in the array of allready seen pictures. These are the functions: function show_pic($pics_voted, $cat, $sex) { srand ((double) microtime() * 1000000); $result = query("SELECT id FROM $cat WHERE sex='$sex'"); while ($row = mysql_fetch_row($result)) { $arr[] = $row[0]; } shuffle($arr); $picture_id = find_id($pics_voted, $arr); echo "picture_id => $picture_id"; return $picture_id; }//show_pic //Hitta id som inte finns bland $pics_voted[] function find_id($pics_voted, $random, $x = 0) { for ($i = 0; $i < count($pics_voted); $i++) { if ($random[$x] == $pics_voted[$i] AND $x >= count($random)) return "no_pics"; //If current key in $random[] is equal to current key in $pics_voted[] AND $x is greater than, or equal to the number of keys in $random[], that is if the last key in $random[] has been reached, return "no_pics" elseif ($random[$x] == $pics_voted[$i]) { find_id($pics_voted, $random, $x+1); //If current key in $random[] is equal to current key in $pics_voted[] run the function again, with $x+1 as an argument to be used in the $random[] array, that is: do the funtion again with the next key in $random[] }//elseif }//for return $random[$x]; }//find_id Does anyone know why this ain't working? I get the same id over and over again. Maybe there is an easuer way to achive what I want? Please help!!