问如何在foreach loop - php - xml中为相同属性值设置条件

EN

<?php
$requestUrl = "url";
$data = simplexml_load_file($requestUrl);
$i=0;
foreach($data->item as $subitem) {
    if(!in_array($data->item[$i]['promocode'], $arr_promocode))
        $arr_promocode[] = $data->item[$i]['promocode'];
    else{
        $key = array_search($data->item[$i]['promocode'], $arr_promocode);
        $data->item[$key]['clicks'] = $data->item[$key]['clicks'] + $subitem->clicks;
    }
    $arr_program[] = $data->item[$i]['program'];
    $arr_program_name[] = $data->item[$i]['program_name'];
    $clicks = $subitem->clicks;
    $total = $subitem->total;
    $i++;
}