Remember, when using require that it is a statement, not a function. It's not necessary to write:
<?php
require('somefile.php');
?>
The following:
<?php
require 'somefile.php';
?>
Is preferred, it will prevent your peers from giving you a hard time and a trivial conversation about what require really is.
PHP - Manual: require
2024-11-13
require
(PHP 4, PHP 5, PHP 7, PHP 8)
require 和 include
几乎完全一样，除了处理失败的方式不同之外。require
在出错时产生 E_COMPILE_ERROR
级别的错误。换句话说将导致脚本中止而 include
只产生警告（E_WARNING），脚本会继续运行。
参见 include 文档了解详情。
add a note
User Contributed Notes 26 notes
chris at chrisstockton dot org ¶
15 years ago
Marcel Baur ¶
10 months ago
If your included file returns a value, you can get it as a result from require(), i.e.
foo.php:
<?php
return "foo";
?>
$bar = require("foo.php");
echo $bar; // equals to "foo"
Anonymous ¶
15 years ago
A note that drove me nuts for 2 days!
Be carfull if you have a newline or blank space befor your php tags in the included/required file it will read as html and outputed.
If your running your output through javascript string evaluations which would be sensitive to newlines/white spaces be carfull that the first chars in the file are the php tages eg <?php
dank at kegel dot com ¶
6 years ago
PHP's require and include seem to differ from C's include in another way: they can't be used in the middle of an expression. e.g.
$ more foo1.php foo2.php
::::::::::::::
foo1.php
::::::::::::::
<?php
print "hello"
.
#"there"
require 'foo2.php';
. "\n";
?>
::::::::::::::
foo2.php
::::::::::::::
"there"
$ php foo1.php
PHP Parse error: syntax error, unexpected '.' in foo1.php on line 6
So php's include operates only on complete statements, whereas c's include operates on bytes of source code.
richardbrenner(-at- )gmx(-)at ¶
17 years ago
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
tjeerd ¶
16 years ago
When using symbolic links with PHP, specify a dotslash './page.php' path to ensure that PHP is looking in the right directory with nested requires:
E.g. when the required actual page1.php contains other require statements to, say page2.php, PHP will search the path that the symbolic link points to, instead of the path where the symbolic link lives. To let PHP find the other page2.php in the path of the symbolic link, a require('./page2.php'); statement will solve the puzzle.
some dot user at notarealdomain dot com ¶
14 years ago
Discovered a bit of weird behavior yesterday involving require() (using PHP 5.2.3). If you use require() inside a function, the "globals" in the file will be local to the function. An example of this:
test.php:
<?php
function TestFunc()
{
require('test2.php');
echo "<pre>" . print_r($GLOBALS, true) . "</pre>";
}
?>
test2.php:
<?php
$MyTestGlobal = Array();
?>
This happens because require is a statement that _inlines_ the target code - not a function that gets called.
To fix this, use the $GLOBALS superglobal:
test2.php:
<?php
$GLOBALS["MyTestGlobal"] = Array();
?>
Wing ¶
12 years ago
if you want always include, require, open files using some 'root' folder based path you may may put file '.htroot' in 'root' folder and use this.
while(!file_exists(getcwd()."/.htroot")){chdir('..');}
This code change current dir to dir where '.htroot' file located and everywhere you can use relative to 'root' paths.
Please avoid absent of '.htroot' file.
scott ¶
14 years ago
If you want to verify that a file can be included or required, the simplest solution I've found is just to check that the file exists.
<?php
if(file_exists($pageContentInc)){
require_once $pageContentInc;
}else{
$pageContentInc = "common/content_404.inc";
require_once $pageContentInc;
}
?>
Does it really need to be any harder than that?
Peter McDonald ¶
14 years ago
re the comment by moazzamk at gmail dot com
As the manual states require and require_once as of PHP 4.02 no longer call the file if the line of code it is on should not be executed.
phpDev a t eSurfers_dot_ com ¶
5 years ago
I didn't find mention that calling return from inside an required file is different than calling return from inside an included file.
return "aaa"; if called in the global scope of an included file will terminate the inclusion and return control to the main file givin "aaa" as a result of the include statement itself.
As far as I have tested (PHP 5.6.10) this does not apply to require
Inc ¶
16 years ago
I have found a problem when I try to access a php file via require($class_directory)
// # $class_directory contain a long full path and dot into the last folder.
// # $class_directory = "/var/.../app/system/plugintoto_1.0/class_plugintoto_1.0.php";
// dot ('.') and minus ('-') are not accepted in require !
webmaster at netgeekz dot net ¶
16 years ago
I have learnt to manipulate this code into an effecitve and easy to use form. I use it with require_once, but it could be used for require.
require_once($_SERVER['DOCUMENT_ROOT'].'/includes/top.php');
This mainly jumps back to the servers document root and then begins to enter the directories defined until it finds the file. In this case it would go back to the root of the server, or whatever your document root is, and then enter includes. there it would search for the top.php file. Simple to use, yet effective...espcially for people like me who re-use code or move files to different directories. I don't have to fix the includes, because they all work the same way.
theunis dot botha1 at gmail dot com ¶
7 years ago
Just for those who may wonder about receiving E_WARNING (in custom error handlers) - PHP generates an E_WARNING when require or require_once fails - and before control returns to your script, it generates an E_COMPILE_ERROR.
So when require() or require_once() fails - don't be surprised to see two messages in your logs (if you have your logging setup this way) - once for the E_WARNING caught by your custom error handler, and once for getting the error from error_get_last() in your shutdown function (which is the actual E_COMPILE_ERROR you were expecting)
dave at davidhbrown dot us ¶
16 years ago
re: danielm at unb dot br...
$_SERVER['DOCUMENT_ROOT'] is very useful, but it is not available with all web servers. Apache has it; IIS doesn't.
I use the following to make my PHP applications work in more situations:
<?php
if (!defined("BASE_PATH")) define('BASE_PATH', isset($_SERVER['DOCUMENT_ROOT']) ? $_SERVER['DOCUMENT_ROOT'] : substr($_SERVER['PATH_TRANSLATED'],0, -1*strlen($_SERVER['SCRIPT_NAME'])));
?>
...but even that gets tripped up by symlinks to different mount points, etc. You could substitute realpath($_SERVER['PATH_TRANSLATED']), but that function has been reported not to work on some (Windows) servers. One could use the PATH_TRANSLATED for both servers, but I figure if Apache is going to tell me exactly what I want to know, I should listen.
gabe at websaviour dot com ¶
15 years ago
If you are experiencing a bug related to using relative paths with include or require, it may be related to a grandparent directory that is executable but not readable. It will cause __FILE__ to return a relative path instead of the full path which it is supposed to show. This manifests itself in interesting ways that can be seemingly unrelated. For instance, I discovered it using the Smarty {debug} command which failed to find its template due to this issue. Please see the following for more details:
http://bugs.php.net/bug.php?id=34552
http://shiftmanager.net/~kurt/test/
danielm at unb dot br ¶
17 years ago
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.
Anonymous ¶
17 years ago
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.
duccio at getlocal dot it ¶
13 years ago
In response to some dot user at notarealdomain dot com:
This is because require executes the code "as if" it was code written inside of the function, inheriting everything including the scope. But here there is something even more interesting:
<requiredfile.php>:
<?php
$this->a.=" is visible also under a require\n";
$b="While the variable b is a local variable of the function\n";
function FunctionUnderRequire() {
echo "But the functions declared inside of a require called from a class function, just as when defined from inside any other function, are always global\n";
}
?>
<mainfile.php>:
<?php
error_reporting(E_ALL|E_STRICT);
class UserClass {
protected $a;
public function UserFunction() {
$this->a='The class variable a';
require 'requiredfile.php';
echo $this->a; // "The class variable a is visible also under a require\n"
echo $this->b; // Notice: Undefined property: UserClass::$b
echo $b; // "While the variable b is a local variable of the function\n"
$this->FunctionUnderRequire(); //Fatal error!
FunctionUnderRequire(); // "But the functions..."
}
}
$UserClass=new UserClass;
$UserClass->UserFunction();
?>
I'm wondering if there is a method for declaring class public/private/protected functions from inside a require/include...
hans at ratzinger dot com ¶
8 years ago
Thanks a lot for this information Brian! This drove me nuts for many hours! This is the first information I found in the web that a white page can be caused by a require -> your script will die if the file is not found!!!
bmessenger at 3servicesolution dot com ¶
15 years ago
// Looks like I might have a fix for some on the
// relative path issue.
if (!function_exists('bugFixRequirePath'))
{
function bugFixRequirePath($newPath)
{
$stringPath = dirname(__FILE__);
if (strstr($stringPath,":")) $stringExplode = "\\";
else $stringExplode = "/";
$paths = explode($stringExplode,$stringPath);
$newPaths = explode("/",$newPath);
if (count($newPaths) > 0)
{
for($i=0;$i<count($newPaths);$i++)
{
if ($newPaths[$i] == "..") array_pop($paths);
}
for($i=0;$i<count($newPaths);$i++)
{
if ($newPaths[$i] == "..") unset($newPaths[$i]);
}
reset($newPaths);
$stringNewPath = implode($stringExplode,$paths).
$stringExplode.implode($stringExplode,$newPaths);
return $stringNewPath;
}
}
}
require_once(bugFixRequirePath("../config.php"));
pedro dot evangelista at gmail dot com ¶
13 years ago
Be careful when using symbolic links, because require will search the real path of the file and not the path relative to the symbolic link.
Imagine your script A.php resides on directory /a and you create a symbolic link for it on directory /b/c.
So for the code
<?php
echo realpath("../");
?>
you might expect the directory /b, but actually you get the root directory /.
If you need to include the file /b/B.php inside your A.php, you can't use the following
<?php
require "../B.php";
?>
because it will search the root directory, not the /b directory.
Regards.
moreau dot marc dot web at gmail dot com ¶
8 years ago
Petit script pour résoudre le problème de l'inclusion dans l'inclusion.
A requiert B qui requiert C -> l'on doit normalement faire correspondre le requiere de B en fonction de l'endroit ou se trouve A dans l'arborescence du site. Pas de souci, sauf si l'on est amené à requérir B depuis une autre page, impossible alors de faire appel au C -> cela retourne une erreur "fichier non trouvé".
Voici une solution qui marche sur tout type de configuration:
Dans B:
<?php
chdir(__DIR__); //Sert à indiquer à PHP le dossier de référence de travail
$file_to_require=realpath('./../../adresse_de_C_relative_par_raport_a_B.php'); //Crée l'adresse absolue de C
require($file_to_require); unset($file_to_require);
?>
daniel at nohair dot com ¶
14 years ago
I love php. But when file can't be included, 'require' or 'require_once' throw fatal error and halt the script, which is almost never desirable on a mission-critical production server. I think it may be better to use something like the following.
<?php
if (@include 'plan_A.php') {
// Plan A;
} elseif (@include 'plan_B.php') {
// Plan B;
} else {
// Hope never happens. If does, then Email the webmaster;
// Call 911, Medic, Fire, Police, the president;
// Change hard drive, server, hosting service;
}
?>
Or handle trouble first is you wish
<?php
if (!@include 'plan_A.php') {
// Someone has kidnapped/corrupted Plan_A.php;
// Email the webmaster;
// Change hard drive, server, hosting service;
} else {
// Plan A;
}
?>
Marc ¶
17 years ago
This will sound elementary, but for C++ native programmers, be sure NOT to put a '#' in front of your include statements! The parser will not give you an error, but also will not include the file, making for a tedious debugging process.
In short, USE:
<?php
include "yourfile.php";
?>
and DON'T use:
<?php
#include "yourfile.php";
?>
ricardo dot ferro at gmail dot com ¶
14 years ago
Two functions to help:
<?php
function add_include_path ($path)
{
foreach (func_get_args() AS $path)
{
if (!file_exists($path) OR (file_exists($path) && filetype($path) !== 'dir'))
{
trigger_error("Include path '{$path}' not exists", E_USER_WARNING);
continue;
}
$paths = explode(PATH_SEPARATOR, get_include_path());
if (array_search($path, $paths) === false)
array_push($paths, $path);
set_include_path(implode(PATH_SEPARATOR, $paths));
}
}
function remove_include_path ($path)
{
foreach (func_get_args() AS $path)
{
$paths = explode(PATH_SEPARATOR, get_include_path());
if (($k = array_search($path, $paths)) !== false)
unset($paths[$k]);
else
continue;
if (!count($paths))
{
trigger_error("Include path '{$path}' can not be removed because it is the only", E_USER_NOTICE);
continue;
}
set_include_path(implode(PATH_SEPARATOR, $paths));
}
}
?>
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