PHP defined() Function
 Complete PHP Misc Reference
Definition and Usage
The defined() function checks whether a constant exists.
Returns TRUE if the constant exists, or FALSE otherwise.
Syntax
| Parameter |
Description |
| name |
Required. Specifies the name of the constant to check |
Example
<?php
define("GREETING","Hello you! How are you today?");
echo defined("GREETING");
?>
|
The output of the code above will be:
Complete PHP Misc Reference
 |
W3Schools' Online Certification Program
The perfect solution for professionals who need to balance work, family, and career building.
More than 4000 certificates already issued!
|
The HTML Certificate documents your knowledge of HTML, XHTML, and CSS.
The JavaScript Certificate documents your knowledge of JavaScript and HTML DOM.
The XML Certificate documents your knowledge of XML, XML DOM and XSLT.
The ASP Certificate documents your knowledge of ASP, SQL, and ADO.
The PHP Certificate documents your knowledge of PHP and SQL (MySQL).
| 
