Description
bool
defined ( string name )
Returns TRUE if the named constant given by
name has been defined,
FALSE otherwise.
Example 1. Checking Constants
<?php /* Note the use of quotes, this is important. This example is checking * if the string 'CONSTANT' is the name of a constant named CONSTANT */ if (defined('CONSTANT')) { echo CONSTANT; } ?>
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See also define(),
constant(),
get_defined_constants(),
function_exists(), and the section on
Constants.