PHP implementation code to obtain the absolute path of the current file

 $basedir = dirname(__FILE__);
 echo $basedir;
 //The absolute path to this file will be printed on the page!
 ?>

Can be used later

define('ROOT', dirname(__FILE__));
require_once ROOT.'/config/conf_mysql.php';

Import files

Several commonly used PHP "Magic constants" Name Description __LINE__ The current line number in the file. __FILE__ The full path and file name of the file. If used in an include file, returns the include file name. As of PHP 4.0.2, __FILE__ always contains an absolute path, while versions before that sometimes contained a relative path. __FUNCTION__ function name (new in PHP 4.3.0). Since PHP 5 this constant returns the name of the function as it was defined (case sensitive). In PHP 4 this value is always lowercase. __CLASS__ The name of the class (new in PHP 4.3.0). Since PHP 5 this constant returns the name of the class when it was defined (case sensitive). In PHP 4 this value is always lowercase. __METHOD__ The method name of the class (newly added in PHP 5.0.0). Returns the name of the method when it was defined (case-sensitive).

Please have a firm grasp of the above and use them more in programming skills.