function getExt1 () {
$url_path = "http://www.sina.com.cn/abc/de/fg.php?id=1";
$temp = pathinfo($url_path, PATHINFO_EXTENSION); // php?id=1
$temp = explode("?", $temp);
echo $temp[0]; // php
}
function getExt2 () {
$url_path = "http://www.sina.com.cn/abc/de/fg.php?id=1";
// ["scheme" => "http","host" => "新浪首页","path" => "/abc/de/fg.php","query" => "id=1"]
$temp = parse_url($url_path);
echo pathinfo($temp['path'], PATHINFO_EXTENSION);
}