獲取文件名後綴

1. 寫一個函數，盡可能高效的，從一個標准 url 裡取出文件的擴展名
例如: http://www.sina.com.cn/abc/de/fg.php?id=1 需要取出 php 或 .php

<? = "http://www.sina.com.cn/abc/de/fg.php?id=1 "//這個是自己寫的
 getUrl( = ('?',  = ([0 = ('.',  [1(getUrl( getExt( = ( = (['path' = (".", [1(getExt( getName( = ( = ['extension'(, ) = ('?',  'start3'.("Y-m-d H:i:s"?>