PHP: List of Keywords

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. The following words cannot be used as constants, class names, or function names. They are, however, allowed as property, constant, and method names of classes, interfaces and traits, except that class may not be used as constant name.

**PHP Keywords**
__halt_compiler()	abstract	and	array()	as
break	callable	case	catch	class
clone	const	continue	declare	default
die()	do	echo	else	elseif
empty()	enddeclare	endfor	endforeach	endif
endswitch	endwhile	eval()	exit()	extends
final	finally	fn (as of PHP 7.4)	for	foreach
function	global	goto	if	implements
include	include_once	instanceof	insteadof	interface
isset()	list()	match (as of PHP 8.0)	namespace	new
or	print	private	protected	public
readonly (as of PHP 8.1.0) *	require	require_once	return	static
switch	throw	trait	try	unset()
use	var	while	xor	yield
yield from

* readonly may be used as function name.

**Compile-time constants**
__CLASS__	__DIR__	__FILE__	__FUNCTION__	__LINE__	__METHOD__
__NAMESPACE__	__TRAIT__

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User Contributed Notes 4 notes

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Thomas Hansen ¶

8 years ago


Please note that reserved words are still not allowed to be used as namespace or as part of it:

<?php
namespace MyNameSpace\List;

class Test
{
}
?>

This will fail with a Parse error:  syntax error, unexpected 'List' (T_LIST), expecting identifier (T_STRING)

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martindilling at gmail dot com ¶

11 years ago


RegEx to find all the keywords:

\b(
(a(bstract|nd|rray|s))|
(c(a(llable|se|tch)|l(ass|one)|on(st|tinue)))|
(d(e(clare|fault)|ie|o))|
(e(cho|lse(if)?|mpty|nd(declare|for(each)?|if|switch|while)|val|x(it|tends)))|
(f(inal|or(each)?|unction))|
(g(lobal|oto))|
(i(f|mplements|n(clude(_once)?|st(anceof|eadof)|terface)|sset))|
(n(amespace|ew))|
(p(r(i(nt|vate)|otected)|ublic))|
(re(quire(_once)?|turn))|
(s(tatic|witch))|
(t(hrow|r(ait|y)))|
(u(nset|se))|
(__halt_compiler|break|list|(x)?or|var|while)
)\b

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Chris ¶

12 years ago


Here they are as arrays:

<?php
$keywords = array('__halt_compiler', 'abstract', 'and', 'array', 'as', 'break', 'callable', 'case', 'catch', 'class', 'clone', 'const', 'continue', 'declare', 'default', 'die', 'do', 'echo', 'else', 'elseif', 'empty', 'enddeclare', 'endfor', 'endforeach', 'endif', 'endswitch', 'endwhile', 'eval', 'exit', 'extends', 'final', 'for', 'foreach', 'function', 'global', 'goto', 'if', 'implements', 'include', 'include_once', 'instanceof', 'insteadof', 'interface', 'isset', 'list', 'namespace', 'new', 'or', 'print', 'private', 'protected', 'public', 'require', 'require_once', 'return', 'static', 'switch', 'throw', 'trait', 'try', 'unset', 'use', 'var', 'while', 'xor');

$predefined_constants = array('__CLASS__', '__DIR__', '__FILE__', '__FUNCTION__', '__LINE__', '__METHOD__', '__NAMESPACE__', '__TRAIT__');
?>

Along with get_defined_functions() and get_defined_constants(), this can be useful for checking eval() statements.

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-32

Johnny D. ¶

4 years ago


const FORBIDDEN_TYPES = [
    'null',

    'bool',
    'false',
    'true',

    'int',
    'float',

    'string',
];

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