constant
(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
constant — Returns the value of a constant
Description
Return the value of the constant indicated by
name.
constant() is useful if you need to retrieve the value of a constant, but do not know its name. I.e. it is stored in a variable or returned by a function.
This function works also with class constants.
Parameters
-
name -
The constant name.
Return Values
Returns the value of the constant.
Errors/Exceptions
If the constant is not defined, an Error exception is thrown.
Prior to PHP 8.0.0, an E_WARNING level error was generated in that case.
Changelog
| Version | Description |
|---|---|
| 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.
|
Examples
Example #1 constant() example
<?php
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!"
?>
See Also
- define() - Defines a named constant
- defined() - Checks whether a given named constant exists
- get_defined_constants() - Returns an associative array with the names of all the constants and their values
- The section on Constants
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