Appendix H. List of Reserved Words

Table of Contents
List of Keywords
Predefined Variables
Predefined Classes
Predefined Constants

The following is a listing of predefined identifiers in PHP. None of the identifiers listed here should be used as identifiers in a your scripts. These lists include keywords and predefined variable, constant, and class names. These lists are neither exhaustive or complete.

List of Keywords

These words have special meaning in PHP. Some of them represent things which look like functions, some look like constants, and so on--but they're not, really: they are language constructs. You cannot use any of the following words as constants, class names, or function names. Using them as variable names is generally OK, but could lead to confusion.

Table H-1. PHP Keywords

and	or	xor	__FILE__	exception	php_user_filter
__LINE__	array()	as	break	case
cfunction	class	const	continue	declare
default	die()	do	echo()	else
elseif	empty()	enddeclare	endfor	endforeach
endif	endswitch	endwhile	eval	exit()
extends	for	foreach	function	global
if	include()	include_once()	isset()	list()
new	old_function	print()	require()	require_once()
return()	static	switch	unset()	use
var	while	__FUNCTION__	__CLASS__	__METHOD__