require vs. require_once function

[reznorsoft]

what is the difference between the require and require_once function 
are there any benefits one has over the other .. and in what circumstance would you opt to use .. well, one rather than the other?

[Cypher7]

something I found via Google...

http://ie.php.net/require_once

I haven't a clue what it means... but might be of use to you!!

[Grudge]

If, for example you used require to output your forum header, everytime you "require'd" that file the header would be output. If you use require_once, every time you call it it knows the file has already been included so won't do anything. require_once is generally more efficient as it stops parsing the same file twice (or more times)

[Tomer]

Yes sometimes if you get a PHP error, try switching to _once and it may solve the problem.

[Christian Land]

create the following 3 files and execute 1.php and 2.php

1.php:

Code Select Expand

<?php

require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');
require('rtfm.php');

?>

2.php:

Code Select Expand

<?php

require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');
require_once('rtfm.php');

?>

rtfm.php:

Code Select Expand

<?php

echo 'reading manuals = knowledge<br />';

?>

[reznorsoft]

thanks for everyone's replies ..

create the following 3 files and execute 1.php and 2.php

and thanks for the visual demo