PHP defined () function
Examples
Check whether a constant presence:
<?php
define("GREETING","Hello you! How are you today?");
echo defined("GREETING");
?>
define("GREETING","Hello you! How are you today?");
echo defined("GREETING");
?>
Running instance »
Definition and Usage
defined () function checks whether a constant presence.
grammar
defined( name )
参数 | 描述 |
---|---|
name | 必需。规定要检查的常量的名称。 |
technical details
return value: | If the constant exists, it returns TRUE, otherwise returns FALSE. |
---|---|
PHP version: | 4+ |
PHP Misc Reference Manual