Is it better to use require_once('filename.php') or require_once 'filename.php';

问题

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

回答1:

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.

回答2:

Pear Coding Standards say :

"include_once and require_once are statements, not functions. Parentheses should not surround the subject filename."

Source : http://pear.php.net/manual/en/standards.including.php

回答3:

What does your heart tell you?

Performance difference, if any: negligible.

回答4:

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

来源：https://stackoverflow.com/questions/3393847/is-it-better-to-use-require-oncefilename-php-or-require-once-filename-php