include - What's better of require(dirname(__FILE__).'/'.'myParent.php') than just require('myParent.php')?

Question

Lots of famous PHP scripts including WordPress use dirname(__FILE__).'/myParent.php' instead of just 'myParent.php' when including files in the same directory of the currently running script.

Aren't they the same thing? Why do you prefer typing more?

Thanks.

Answer 1

PHP needs to know the absolute path to the file. dirname(__FILE__).'/myParent.php' already is the absolute path but 'myParent.php' requires a lookup using the given paths in include_path to get an absolute path and find the file. A better choice would be './myParent.php':

However, it is more efficient to explicitly use include './file' than having PHP always check the current directory for every include.