constant
(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
constant — Returns the value of a constant
Description
constant(string $name): mixed
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
An Error exception is thrown, if the constant is not defined. 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!" ?>
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https://www.php.net/manual/en/function.constant.php