PHP is a solid magic __dir__

We know that PHP provides a magic constant (magic constant) __file__ that points to the currently executing PHP script. However, PHP does not directly provide a constant for the directory where the script resides. That is, if we want to get the directory where the current PHP script resides, we need to use the DirName () function:

<?php

$dir =dirname (__file__);

?>

In PHP5.3, a new constant __dir__ is added, pointing to the directory where the PHP script is currently executing.

For example, the currently executing PHP file is/www/website/index.php

Then __file__ equals '/www/website/index.php '

and __dir__ equals '/www/website '

Now we want to include the files in the current file directory or subdirectories, which can be used directly:

We will require absolute path in actual development, so we will set some

Define (' Root_path ', __dir__) '

So there's a song about a constant in the root directory you can use this constant to set the absolute path of some other directories.

PHP is a solid magic __dir__