Deprecated: preg_split():

Question

I have this code for current url:

$core = preg_split('@/@', str_replace($_SERVER['DOCUMENT_ROOT'], '', realpath(dirname(__FILE__))), NULL, PREG_SPLIT_NO_EMPTY);

On php 8.1.x the problem in this line say:

"Deprecated: preg_split(): Passing null to parameter #3 ($limit)"

I would appreciate some help to fix the problem in my code.

The original code is here:

https://stackoverflow.com/a/20075147/3673405