PHP - is it better to use require_once('filename.php') or require_once 'filename.php';

Question

Is this just a stylistic difference, or does using require_once('filename.php') vs require_once 'filename.php' have actual load/efficiency differences?

Answer 1

What does your heart tell you?

Performance difference, if any: negligible.

Answer 2

It's exactly the same thing. It's a matter of style.

The parentheses may get in the way some times. For instance, this example from the manual doesn't do what you expect:

if (include('vars.php') == 'OK') {
    echo 'OK';
}

See example #4.

Answer 3

There is no difference. I don't use the brackets 'cause they are not necessary. require_once is no function.