php - 函数require-once无法找到文件

I am implementing a code where visitors can email our company.

in my gmail.php, it has this code for line 11

require_once('PHPMailerAutoload.php') or exit();

the error it gives is when i run it is

Warning: require_once(1) [function.require-once]: failed to open stream: No such file or directory in /home/maxsell/public_html/php/gmail.php on line 11

Fatal error: require_once() [function.require]: Failed opening required '1' (include_path='/home/maxsell/php:.:/usr/lib/php:/usr/local/lib/php') in /home/maxsell/public_html/php/gmail.php on line 11

and if i click on [function.require-once] it loads

The requested URL /php/function.require-once was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I made this in our other website and it worked there. I tried changing file path in require_once but it doesn't work. gmail.php and PHPMailerAutoload.php is in the same folder.

edit: here is a directory contents directory contents

The problem is the or exit()-part.

when i use

require_once("test.php") or exit();

i get the same error, but

require_once("test.php");

works if the file exists, or throws a correct error if it doesn't.

also, the common syntax is

require_once "test.php";

and the or exit() part is superfluous anyway, since require quits the script itself if the file is not found.

edit:

after some testing i suspect that the internal workings of this curious error is that require_once is not a function but a command structure, meaning that

require_once('PHPMailerAutoload.php') or exit();

is functionally the same as

require_once ('PHPMailerAutoload.php' or exit());

since the or-operator takes precedence.

which makes your require fail because ('PHPMailerAutoload.php' or exit()) resolves to true, effectively making php try to require(true) which must fail.

you can use this one and hope this will work for you

require_once($_SERVER['DOCUMENT_ROOT'].'/phpmailerfoldername/PHPMailerAutoload.php');