今天调试一个PHP程序，突然发现某个PHP文件不执行，而是输出源码，后来检查发现，是短标签的问题。因为在PHP.INI文件中已经默认把短标签只识别支持默认关闭掉了。要解决问题，只需要打开即可，或者直接把<? 改成 <?php。

问题现象：

<?php echo “123”; ?>可以执行

<? echo “123”; ?>却直接输出源码。

解决办法：

在PHP.INI文件中，查找<?或short_open_tag，有下面信息提示，意思是是否打开短标签识别，而且已经推荐大家使用完整封堵标签<?php and ?>，尽量不要使用短标签<? and ?>。

; This directive determines whether or not PHP will recognize code between
; <? and ?> tags as PHP source which should be processed as such. It’s been
; recommended for several years that you not use the short tag “short cut” and
; instead to use the full <?php and ?> tag combination. With the wide spread use
; of XML and use of these tags by other languages, the server can become easily
; confused and end up parsing the wrong code in the wrong context. But because
; this short cut has been a feature for such a long time, it’s currently still
; supported for backwards compatibility, but we recommend you don’t use them.
; Default Value: On
; Development Value: Off
; Production Value: Off
; http://php.net/short-open-tag
short_open_tag = Off

; Allow ASP-style <% %> tags.
; http://php.net/asp-tags
asp_tags = Off

把以上设置short_open_tag = Off改成short_open_tag = On即可，当然asp_tags如果是On要改成Off关闭。