官方稳定

当解析一个文件时，PHP 会寻找起始和结束标记，也就是 ，这告诉 PHP 开始和停止解析二者之间的代码。此种解析方式使得 PHP 可以被嵌入到各种不同的文档中去，而任何起始和结束标记之外的部分都会被 PHP 解析器忽略。

PHP 也允许使用短标记 ，但不鼓励使用。只有通过激活 php.ini 中的 short_open_tag 配置指令或者在编译 PHP 时使用了配置选项 --enable-short-tags 时才能使用短标记。

如果文件内容是纯 PHP 代码，最好在文件末尾删除 PHP 结束标记。这可以避免在 PHP 结束标记之后万一意外加入了空格或者换行符，会导致 PHP 开始输出这些空白，而脚本中此时并无输出的意图。

I would like to stress out that the opening tag is "

would not work, as mentioned, but :

will work, as well as :

and :

I just wanted to clarify this to prevent anyone from misreading purkrt’s note to mean that a the opening tag --even when being on its own line–required a space ( \s ) character. The following would work but is not at all necessary or how the earlier comment should be interpreted :

The end-of-line character is whitespace, so it is all that you would need.