Misc. Functions
PHP Manual

define

Defines a named constant

Description

bool define ( string $name , mixed $value [, bool $case_insensitive = false ] )

Defines a named constant at runtime.

Parameters

name

The name of the constant.

value

The value of the constant. In PHP 5, value must be a scalar value (integer, float, string, boolean, or NULL). In PHP 7, array values are also accepted.

Warning

While it is possible to define resource constants, it is not recommended and may cause unpredictable behavior.

case_insensitive

If set to TRUE, the constant will be defined case-insensitive. The default behavior is case-sensitive; i.e. CONSTANT and Constant represent different values.

Note:

Case-insensitive constants are stored as lower-case.

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version Description
7.0.0 array values are allowed.

Examples

Example #1 Defining Constants

<?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.

define("GREETING", "Hello you.", true);
echo GREETING; // outputs "Hello you."
echo Greeting; // outputs "Hello you."

// Works as of PHP 7
define('ANIMALS', array(
    'dog',
    'cat',
    'bird'
));
echo ANIMALS[1]; // outputs "cat"

?>

See Also