PHP basename( DIR ) is returning _DIR_ on some servers

I'm hoping someone here knows the answer to this. I wrote a script that uses

basename( __DIR__ )

then uses an if file exist function.

On my server this works fine, however on other sever it actually returns the word _DIR_ instead of the file path.

Did this change with a version of PHP or is there some other setting that makes it so this doesn’t work?

Lastly is there a better way to get the path of the file? Here is the whole line I’m using:

define('NIFTY_CONSTANT', trailingslashit (WP_PLUGIN_DIR . '/'. basename( __DIR__ ) ). '/lib/mdetect.php' );

(yes I know it's a WordPress function but this is not a WordPress question it's a PHP one)

Solution

__DIR__ is introduced in PHP 5.3 . Double check your PHP version .

PHP basename( __DIR__ ) is returning _DIR_ on some servers