PHP File & Directory Constants


Example

Current file

You can get the name of the current PHP file (with the absolute path) using the __FILE__ magic constant. This is most often used as a logging/debugging technique.

echo "We are in the file:" , __FILE__ , "\n";

Current directory

To get the absolute path to the directory where the current file is located use the __DIR__ magic constant.

echo "Our script is located in the:" , __DIR__ , "\n";

To get the absolute path to the directory where the current file is located, use dirname(__FILE__).

echo "Our script is located in the:" , dirname(__FILE__) , "\n";

Getting current directory is often used by PHP frameworks to set a base directory:

// index.php of the framework

define(BASEDIR, __DIR__); // using magic constant to define normal constant

// somefile.php looks for views:

$view = 'page';
$viewFile = BASEDIR . '/views/' . $view;

Separators

Windows system perfectly understands the / in paths so the DIRECTORY_SEPARATOR is used mainly when parsing paths.

Besides magic constants PHP also adds some fixed constants for working with paths:

  • DIRECTORY_SEPARATOR constant for separating directories in a path. Takes value / on *nix, and \ on Windows. The example with views can be rewritten with:
$view = 'page';
$viewFile = BASEDIR . DIRECTORY_SEPARATOR .'views' . DIRECTORY_SEPARATOR . $view;
  • Rarely used PATH_SEPARATOR constant for separating paths in the $PATH environment variable. It is ; on Windows, : otherwise