DEFINED(3) 1 DEFINED(3)
defined - Checks whether a given named constant exists
SYNOPSIS
bool defined (string $name)
DESCRIPTION
Checks whether the given constant exists and is defined.
Note
If you want to see if a variable exists, use isset(3) as defined(3) only applies to constants. If you want to see if a function
exists, use function_exists(3).
PARAMETERS
o $name
- The constant name.
RETURN VALUES
Returns TRUE if the named constant given by $name has been defined, FALSE otherwise.
EXAMPLES
Example #1
Checking Constants
<?php
/* Note the use of quotes, this is important. This example is checking
* if the string 'TEST' is the name of a constant named TEST */
if (defined('TEST')) {
echo TEST;
}
?>
SEE ALSO
define(3), constant(3), get_defined_constants(3), function_exists(3), The section on Constants.
PHP Documentation Group DEFINED(3)
