Why ./ is not being recognized as current directory in my php file?

问题

I have the following file hierarchy:

and the require_once is somehow not working (Warning: require_once(./AutentificadorJWT.php): failed to open stream: No such file or directory in C:\xampp\htdocs\clases\usuario.php on line 2) As far as I know ./ points to the current directory. Now the following works: require_once 'AutentificadorJWT.php'; Why ./ is not working?

回答1:

It can be quite difficult to know what directory is the current directory when you have a complex hierarchy of code. If you want to have a constant point of reference, then you can use $_SERVER['DOCUMENT_ROOT'] which defines the base of your code on your computer. So...

require_once $_SERVER['DOCUMENT_ROOT'].'/base.php';

Will work for base.php in the root of your project. The one problem I've had with this is that unit testing doesn't always have a lot of the $_SERVER variables set.

Alternatively, you can use __DIR__ which is the directory of the current file. So if in your case you changed it to ...

require_once __DIR__.'/AuthentifacdorJWT.php';

This will always be relative to the directory of the file your working with.

来源：https://stackoverflow.com/questions/46009282/why-is-not-being-recognized-as-current-directory-in-my-php-file