http://item.taobao.com/item.htm?id=16866631720&ali_trackid=2:mm_1463_0_0:1357875437_410_201055913&spm=2014.1
这是淘宝的链接，怎样拿到里面的id参数呢？，位置不一定在那的
------解决方案--------------------
$s = 'http://item.taobao.com/item.htm?id=16866631720&ali_trackid=2:mm_1463_0_0:1357875437_410_201055913&spm=2014.1';
parse_str(substr($s, strpos($s, '?')+1), $ar);
print_r($ar);
array
(
[id] => 16866631720
[ali_trackid] => 2:mm_1463_0_0:1357875437_410_201055913
[spm] => 2014.1
)