php4 用的是 <? ?> 定义边界符

php5 用的是 <?php ?> 来定义的

所以不执行，得改好多文件

打开 php.ini 找到以下代码，把 off 改成 on 重起服务，两个就都可以用了。

; Allow the <? tag. Otherwise, only <?php and <script> tags are recognized.
; NOTE: Using short tags should be avoided when developing applications or
; libraries that are meant for redistribution, or deployment on PHP
; servers which are not under your control, because short tags may not
; be supported on the target server. For portable, redistributable code,
; be sure not to use short tags.

short_open_tag = off