Developer Forums | About Us | Site Map
Search  
HOME > PHPMANUAL


Sponsors





Web Host
site hosted by netplex
Partners

Online Manuals

defined

(PHP 3, PHP 4 )

defined --  Checks whether a given named constant exists

Description

bool defined ( string name)

Returns TRUE if the named constant given by name has been defined, FALSE otherwise.

Example 1. Checking Constants

<?php
/* Note the use of quotes, this is important.  This example is checking 
 * if the string 'CONSTANT' is the name of a constant named CONSTANT */
if (defined('CONSTANT')) {
    echo CONSTANT;
}
 ?>

Note: If you want to see if a variable exists, use isset() as defined() only applies to constants. If you want to see if a function exists, use function_exists().

See also define(), constant(), get_defined_constants(), function_exists(), and the section on Constants.

Copyright 2004-2017 GrindingGears.com. All rights reserved. Site hosted by NETPLEX