I was working with WordPress and I required to include require_once('./blog/wp-blog-header.php'); to use WordPress functions outside WordPress when I noticed this strange behavior.
When I'm using include "file_name" or require_once "file_name" things are working fine, but if I try to use () then the rest is a blank page. no result or errors at all.
I faced the same problem earlier but I forgot how that was solve. Is there any reason behind this or this is just happening to me?
This is very weird, include and include() should be equivalent. Nevertheless, include, include_once, require and require_once are special language constructs not functions, parentheses are not needed (and IMHO should not be used).
For example, taken from PHP documentation:
Note: Because this is a language construct and not a function, it cannot be called using variable functions.