getid3_lib::fileextension( string $filename, int $numextensions = 1 ): string

608	public static function fileextension($filename, $numextensions=1) {609		if (strstr($filename, '.')) {610			$reversedfilename = strrev($filename);611			$offset = 0;612			for ($i = 0; $i < $numextensions; $i++) {613				$offset = strpos($reversedfilename, '.', $offset + 1);614				if ($offset === false) {615					return '';616				}617			}618			return strrev(substr($reversedfilename, 0, $offset));619		}620		return '';621	}