S 1en__, is the full path and file name of the return file. If used in an include file, the include file name is returned. Starting with PHP 4.0.2, s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s = s S 4en (s 5en__), returning part of the current file path, that is, removing the file name.

Demo code:

<?php
 //  Gets the current path to the file  +  The file name
 echo __FILE__;
 echo '<BR>';
 //  Gets the current path to the file
 echo dirname(__FILE__);
 echo '<BR>';
 //  Gets on the file 1 Level directory path
 echo dirname(dirname(__FILE__));
?>

Operation results:

D:\wamp\www\index.php
D:\wamp\www
D:\wamp

S: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s: s.