PHP defined() Function

PHP Misc Reference PHP Misc Reference

Example

Check if a constant exists:

<?php
define("GREETING","Hello you! How are you today?");
echo defined("GREETING");
?>

Run example »

Definition and Usage

The defined() function checks whether a constant exists.


Syntax

defined(name)

Parameter Description
name Required. Specifies the name of the constant to check

Technical Details

Return Value: Returns TRUE if the constant exists, or FALSE otherwise
PHP Version: 4+

PHP Misc Reference PHP Misc Reference

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