constant
(PHP 4 >= 4.0.4, PHP 5)
constant — Returns the value of a constant
说明
mixed constant ( string $name )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.
参数
- name
-
The constant name.
返回值
Returns the value of the constant, or NULL if the constant is not defined.
错误/异常
An E_WARNING level error is generated if the constant is not defined.
范例
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!"
?>
参见
