require()

The require() statement includes and evaluates the specific file.

require() includes and evaluates a specific file. Detailed information on how this inclusion works is described in the documentation for include().

require() and include() are identical in every way except how they handle failure. include() produces a Warning while require() results in a Fatal Error. In other words, don't hesitate to use require() if you want a missing file to halt processing of the page. include() does not behave this way, the script will continue regardless. Be sure to have an appropriate include_path setting as well.

Example 16-4. Basic require() examples

<?php require 'prepend.php'; require $somefile; require ('somefile.txt'); ?>

See the include() documentation for more examples.

Note: Prior to PHP 4.0.2, the following applies: require() will always attempt to read the target file, even if the line it's on never executes. The conditional statement won't affect require(). However, if the line on which the require() occurs is not executed, neither will any of the code in the target file be executed. Similarly, looping structures do not affect the behaviour of require(). Although the code contained in the target file is still subject to the loop, the require() itself happens only once.

Note: Because this is a language construct and not a function, it cannot be called using variable functions

Warning

Windows versions of PHP prior to PHP 4.3.0 do not support accessing remote files via this function, even if allow_url_fopen is enabled.

User Contributed Notes
require

Marc
06-May-2005 01:42


This will sound elementary, but for C++ native programmers, be sure NOT to put a '#' in front of your include statements! The parser will not give you an error, but also will not include the file, making for a tedious debugging process.



In short, USE:

<?php

     include "yourfile.php";

?>



and DON'T use:

<?php

     #include "yourfile.php";

?>

richardbrenner(-at- )gmx(-)at
07-Apr-2005 04:58


If you use relativ paths in a php script (file A) that can be required by another php script (file B), be aware that the relativ paths in file A will be relativ to the directory, where file B is stored. 

You can use the following syntax in file A, to be sure that the paths are relativ to the directory of file A:



<?

require(dirname(__FILE__)."/path/relative/file_to_include.php");

?>



Greetings,

Richard

10-Feb-2005 01:29


Note when calling any require or include function, that the call will block if the script given as the parameter is excecuting.

Because of this one should be careful when using blocking functions like sleep() in a script which is included by another.

danielm at unb dot br
22-Nov-2004 02:50


if you want to include files with an absolut path reference, you can use:



require ($_SERVER["DOCUMENT_ROOT"]."/path/to/file.php");



this way you can organize your files in subdirectories trees.

jaisen - at - jmathai - dot - com
12-Mar-2004 03:10


NOTE: This function changed how it worked.  In PHP 3 this behaved very differently than it does on PHP 4.  Require used to include and parse the file regardless where the require line was positioned.



For example (PHP3):



<?php

  if(false){ require 'file_does_not_exist.php'; }

?>



That code throw a fatal exception even though it's in a conditional block which evaluates to false.  In PHP 4 the file is never included or parsed, so no exception is thrown.



For example (PHP4)

<?php

  if(false){ require '1_file_does_not_exists.php'; }

  require '2_file_does_not_exists.php';

?>



Stops execution of the script on trying to require the 2nd file...by bypasses the first require.



--JM