constant()
constant() — Returns the value of a constant.
Built-in function of PHP 8.5. The manual lists it as available in PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.
Signature
constant(string $name): mixed
Parameters
| Parameter | Type | What it takes |
|---|---|---|
| $name | string | The constant name. |
Return value
Returns the value of the constant.
Example
A runnable snippet:
define("MAXSIZE", 100); echo MAXSIZE; echo constant("MAXSIZE"); // same thing as the previous line interface bar { const test = 'foobar!'; } class foo { const test = 'foobar!'; } $const = 'test'; var_dump(constant('bar::'. $const)); // string(7) "foobar!" var_dump(constant('foo::'. $const)); // string(7) "foobar!"
Changelog
| Version | Change |
|---|---|
| 8.0.0 | If the constant is not defined, constant() now throws an Error exception; previously an E_WARNING was generated, and null was returned. |
See also
define(), defined(), get_defined_constants()
All PHP 8.5 built-in functions
Reference card built from the PHP manual page constant() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.