得到一个xml型的对象：
$resp = $this->c->execute($req, $sessionKey);//获得xml对象
$items=$resp->items;
那么读取对象的值，就用$items->item，或者$items->item->price，如此操作很不方便，不符合php操作数组的习惯。
php提供了array方法将对象转换成数组，只要把你要转换数组的对象前面加上（array）就行了。
比如将$items->item（有很多item的对象）转换成数组：
foreach ($items->item as $item){
$goods[]=(array)$item;
}
$goods就是一个php数组了。
转换前：
SimpleXMLElement Object
(
[cid] => 50003793
[modified] => 2013-04-18 17:16:25
[nick] => qq307819623
[price] => 200.00
[title] => Nokia N97全新行货
)
SimpleXMLElement Object
(
[cid] => 50024921
[modified] => 2013-04-18 16:58:06
[nick] => qq307819623
[pic_url] =>pic.jpg
[price] => 888888.00
[title] => 刘俊仲
)
SimpleXMLElement Object
(
[cid] => 1512
[modified] => 2013-04-18 16:56:46
[nick] => qq307819623
[pic_url] => item_pic.jpg
[price] => 323232.00
[title] => 二手你好
)
SimpleXMLElement Object
(
[cid] => 50012166
[modified] => 2013-04-18 15:10:07
[nick] => qq307819623
[pic_url] =>0-item_pic.jpg
[price] => 32.00
[title] => 放大率拉德斯基分拉沙德疯了似的看法拉斯法
)
转换后：
Array
(
[0] => Array
(
[cid] => 50003793
[modified] => 2013-04-18 17:16:25
[nick] => qq307819623
[price] => 200.00
[title] => Nokia N97全新行货
)
[1] => Array
(
[cid] => 50024921
[modified] => 2013-04-18 16:58:06
[nick] => qq307819623
[pic_url] => pic.jpg
[price] => 888888.00
[title] => 刘俊仲
)
[2] => Array
(
[cid] => 1512
[modified] => 2013-04-18 16:56:46
[nick] => qq307819623
[pic_url] =>item_pic.jpg
[price] => 323232.00
[title] => 二手你好
)
[3] => Array
(
[cid] => 50012166
[modified] => 2013-04-18 15:10:07
[nick] => qq307819623
[pic_url] => 0-item_pic.jpg
[price] => 32.00
[title] => 放大率拉德斯基分拉沙德疯了似的看法拉斯法
)