The difference between __FILE__ and $_SERVER['SCRIPT_FILENAME']

echo $_SERVER['SCRIPT_FILENAME'].'';
echo __FILE__;

Execute a.php to get:

require 'a.php';

and execute b.php, the result is:

E:/var/www/b.php ($_SERVER['SCRIPT_FILENAME']) E:wampwwwTexta.php (__FILE__)

From this, we can draw the difference between the two: $_SERVER['SCRIPT_FILENAME'] The absolute path and file name of the currently executing program __FILE__ The absolute path and file name of the original file (included file)

Dear, do you understand? Regarding the difference between __FILE__ and $_SERVER['SCRIPT_FILENAME'], please understand the meaning contained in the above example.