PHP Keywords

PHP has a set of keywords that are reserved words which cannot be used as function names, class names or method names. Prior to PHP 7, these keywords could not be used as class property names either:

Keyword	Description
abstract	Declare a class as abstract
and	A logical operator
as	Used in the foreach loop
break	Break out of loops and switch statements
callable	A data type which can be executed as a function
case	Used in the switch conditional
catch	Used in the try..catch statement
class	Declare a class
clone	Create a copy of an object
const	Define a class constant
continue	Jump to the next iteration of a loop
declare	Set directives for a block of code
default	Used in the switch statement
do	Create a do...while loop
echo	Output text
else	Used in conditional statements
elseif	Used in conditional statements
empty	Check if an expression is empty
enddeclare	End a declare block
endfor	End a for block
endforeach	End a foreach block
endif	End an if or elseif block
endswitch	End a switch block
endwhile	End a while block
extends	Extends a class or interface
final	Declare a class, property or method as final
finally	Used in the try...catch statement
fn	Declare an arrow function
for	Create a for loop
foreach	Create a foreach loop
function	Create a function
global	Import variables from the global scope
goto	Jump to a line of code
if	Create a conditional statement
implements	Implement an interface
include	Embed code from another file
include_once	Embed code from another file
instanceof	Test an object's class
insteadof	Resolve conflicts with traits
interface	Declare an interface
isset	Check if a variable exists and is not null
list	Assigns array elements into variables
namespace	Declares a namespace
new	Creates an object
or	A logical operator
print	Output text
private	Declare a property, method or constant as private
protected	Declare a property, method or constant as protected
public	Declare a property, method or constant as public
require	Embed code from another file
require_once	Embed code from another file
return	Exit a function and return a value
static	Declare a property or method as static
switch	Create a switch block
throw	Throw an exception
trait	Declare a trait
try	Create a try...catch structure
unset	Delete a variable or array element
use	Use a namespace
var	Declare a variable
while	Create a while loop or end a do...while loop
xor	A logical operator
yield	Used in generator functions
yield from	Used in generator functions

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