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__