Anything wrong with "in_array"

function characterData($parser, $data) { global $item; global $returnedArray; $data= trim($data); if($item){ // echo var_dump($data); //echo var_dump($returnedArray); if(!in_array($data,$returnedArray)){ $returnedArray[]=$data; } } } As above , I try to use in_array to avoid duplication. It works vell on my own machine which runs PHP HOME version. However, when I run it on University machine(php4.1.2), a warning is give: Warning: Wrong datatype for second argument in call to in_array in /home/yang/test/1.php on line 33 Auckland Beijing Berlin Birmingham Chicago Darwin Dublin Edmonton Hong Kong London Manchester Melbourne Moscow New York Newcastle Oslo Ottawa San Diego San Francisco Seattle Shanghai Sydney Tokyo So, is there anything wrong with in_array I used? Cheers! Yang