Defines a named constant
Syntax
define(string $constant_name, mixed $value): bool
Parameters
constant_name
The name of the constant.
Note: It is possible to define() constants with reserved or even invalid names, whose value can (only) be retrieved with constant(). However, doing so is not recommended.
value
The value of the constant.
Warning: While it is possible to define resource constants, it is not recommended and may cause unpredictable behavior.
Return
Returns TRUE on success or FALSE on failure.
Examples
constant_name value | null
<?
define("MYCONSTANT", null);
var_export(MYCONSTANT);
?>
NULL
constant_name value | boolean
<?
define("MYCONSTANT", true);
var_export(MYCONSTANT);
?>
true
constant_name value | float
<?
define("MYCONSTANT", 0.1);
echo MYCONSTANT;
?>
0.1
constant_name value | integer
<?
define("MYCONSTANT", 1);
echo MYCONSTANT;
?>
1
constant_name value | string
<?
define("MYCONSTANT", "Hello World!");
echo MYCONSTANT;
?>
Hello World!
constant_name value | array
<?
define("MYCONSTANT", array(0, 1));
print_r(MYCONSTANT);
?>
Array
(
[0] => 0
[1] => 1
)
Return
<?
$return = define("MYCONSTANT", array(0, 1));
var_export($return);
?>
true
