__LINE__
The __LINE__ magic constant displays the current line number of the file.
Demo:
This is line #17__FILE__
This magic constant can be used to display the full path of the current file.
Demo:
The full path of this file is: /var/www/vhosts/mpino.bitweb1.nwtc.edu/httpdocs/php/research-documentation/02-php.net.php__DIR__
The __DIR__ will display the current directory of this file. If it was used in an include file, it would return the directory of that file.
Demo:
Current file directory /var/www/vhosts/mpino.bitweb1.nwtc.edu/httpdocs/php/research-documentation/n__FUNCTION__
The __FUNCTION__ magic constant returns the name of the function being called.
Demo:
The Magic Constant name is: magicConstantFunction