附录 J. 保留字列表

以下是 PHP 中预定义标识符的列表。没有列在下面的标识符可以在脚本中作为自定义标识符使用。这些列表包括关键字和预定义变量、常量和类名。这些列表可能有遗漏,它是不完整的。

关键词列表

这些词语在 PHP 中有着特殊的意义。它们中有些像是函数,有些像是常量……但是它们不是的,它们只是语言结构的一部分。不能使用它们的任何一个作为常量、方法名或是类名。但是可以将它们作为变量名使用,不过这样会导致混淆。


add a note add a note User Contributed Notes
01-Nov-2006 08:42
Two things:

1. It would be nice for this list to differentiate those reserved words, which are language constructs used *with* parentheses (isset, unset, empty, eval, exit, die, ...) and those rather to be used *without* parentheses (all includes, echo, print, return, ...?)

This would really help define some common coding styles...

2. Do you write NULL, TRUE, FALSE or null, true, false? (I find CAPITAL letters better, however typing them can be annoying so I stick with using all lowercase letters, but what's the standard?)
al dot barrett at gmail dot com
05-May-2006 12:38
The list also seems to be missing both "parent" and "self" as well.
wsapplegate at IHATESPAM dot myrealbox dot com
01-Feb-2006 01:32
I also can't find the NULL keyword in the list. The `extends' keyword is mentioned twice, too.
10-Jan-2006 07:41
I don't see the boolean constants 'true' and 'false' listed among the reserved words/keywords/constants.