include

The include() statement includes and evaluates the specified file.

The documentation below also applies to require(). The two constructs are identical in every way except how they handle failure. They both produce a Warning, but require() results in a Fatal Error. In other words, 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. Be warned that parse error in included file doesn't cause processing halting in PHP versions prior to PHP 4.3.5. Since this version, it does.

Files for including are first looked for in each include_path entry relative to the current working directory, and then in the directory of current script. E.g. if your include_path is libraries, current working directory is /www/, you included include/a.php and there is include "b.php" in that file, b.php is first looked in /www/libraries/ and then in /www/include/. If filename begins with ./ or ../, it is looked only in the current working directory.

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 7.5. Basic include() example

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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 7.6. Including within functions

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<?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 fopen wrappers" are enabled in PHP (which they are in the default configuration), you can specify the file to be included using a URL (via HTTP or other supported wrapper - see Appendix O, List of Supported Protocols/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.

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.

Example 7.7. include() through HTTP

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<?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';

$foo = 1;
$bar = 2;

include 'file.txt';  // Works.
include 'file.php';  // Works.

?>

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: 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 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 7.8. Comparing return value of include

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

    echo 'OK';

}

// works
if ((include 'vars.php') == 'OK') {

    echo 'OK';

}
?>

Note:

In PHP 3, the return may not appear inside a block unless it's a function block, in which case the return() applies to that function and not the whole file.

Example 7.9. include() and the return() statement

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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 5 issues fatal error because functions were already declared, while PHP 4 doesn't complain about functions defined after return(). 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 7.10. Using output buffering to include a PHP file into a string

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<?php

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


function get_include_contents($filename) {

    if (is_file($filename)) {

        ob_start();

        include $filename;

        $contents = ob_get_contents();

        ob_end_clean();

        return $contents;

    }

    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

Related Examples ( Source code ) » include

Code Examples / Notes » include

This is a good example for returning a value from an included file I think. I'm working on my own template class like Smarty. This class gets html code from template files. Then it creates a file that will be included directly. It displays only installed modules for the page. The included page always checks the installed modules. If the comparision returns false, the included file returns FALSE and warns the class to recreate itself. Then a new file with requested modules will be overwritten to the existing one. Here is the main framework of my class: <?php /* by Safak Ozpinar */ class MyInclude { private $modules = array(); private $numModules = 0; /* the constructor gets module names into an array */ function MyInclude($inputModules) { if(!is_array($inputModules)) $inputModules = array($inputModules); foreach($inputModules as $module) { $this->modules[$this->numModules] = $module; $this->numModules++; } } /* the main action happens here, check carefully */ function Display($fname, $reCreate = FALSE) { if(@file_exists($fname) && !$reCreate) { // if the included file returns FALSE, recreate it if((include $fname)==FALSE) { $this->Display($fname, TRUE); return; } } else { $this->Create($fname); include($fname); } } /* the behavior of the method Create depends on the format of your template file */ // you will need some changes on this method to adapt to your work private function Create($fname) { $contentsPHP = '<?'."\n"; $contentsHTML = '<html><body>'."\n"; foreach($this->modules as $module) { $contentsPHP .= '$storedModules[] = \''.$module.'\';'."\n"; // the html code of the module (you may need to take from a tempate file) $contentsHTML .= ' HTML code for module <b>"'.$module.'"</b>'."\n"; } // here is the comparision code for included file // if the comparision returns FALSE, the file also returns FALSE $contentsPHP .= 'if(!$this->Compare($storedModules)) return FALSE;'."\n"; $contentsPHP .= '?>'."\n"; $contentsHTML .= '</body></html>'; $fp = fopen($fname,'wb'); fwrite($fp, $contentsPHP.$contentsHTML); fclose($fp); } /* ordered comparision, you may want to change the operations in this method */ function Compare($storedModules) { $count = count($storedModules); if($count == $this->numModules) { for($i=0; $i<$count; $i++) { if(strcmp($storedModules[$i],$this->modules[$i])!=0) return FALSE; } return TRUE; } else return FALSE; } } /* lets go */ $tpl = new MyInclude(array('headline','main_menu','sub_menu','text_ads')); $tpl->Display('inc.php'); ?> I haven't written error controls here because the code would be too large. For instance; if a html template for requested modules doesn't exist, you may want to display an error message or make some operations. --- Safak Ozpinar (from Istanbul University)

In reference to the fopen() and $use_include_path workaround for checking whether a include file exists as posted by [arnold at bean-it dot nl]... I did some benchmarks with 100 dirs (each with 1 file) in the include_path on Apache/2.0.55 (Win32) PHP/5.2.1. Here are the results: (note: in the success scenarios, I am include'ing the file in the LAST directory on the include stack. This is to maximize the seek time; fail scenarios simply use a non-existent file; all times are in seconds ) benchmarks --> plain vanilla INCLUDE (success) 0.05515718460083 0.054859161376953 0.053768157958984 (fail) 0.22402501106262 0.17378783226013 0.14510798454285 benchmarks --> fopen() and $use_include_path workaround (success) 0.060588836669922 0.069549798965454 0.056423902511597 (fail) 0.05295991897583 0.039775133132935 0.054499864578247 >>> CONCLUSION In cases involving MANY include paths, include() is -marginally- faster than the workaround (unsurprising - we incur the extra overhead of BOTH the fopen() call AND the $use_include_path seek). I say marginal in comparison to the "fail" scenarios, detailed next.. The most surprising thing is the inefficiency of include() when you are trying for a non-existent file. As compared to the workaround, the native include() method is roughly 3 times slower. Based on additional tests (50 paths only), I note that any decrease in seek time for either case is generally linear to the number of paths. --- THEREFORE, depending on the amount of paths you have, you might want to resort to different methods of optimizing the includes in your scripts, especially if you need to constantly test for the existence of include'd files (our organization uses a templating engine that relies on a virtual flat directory structure using the set_include_path() function). --- From a technical perspective, I have no idea why this is the case and I find the prospect of trawling the PHP source to be rather daunting. However, as an educated guess: I figure that the include() code assumes the file exists, and so wastes processor cycles making a system read call, which inevitably fails. For those interested in the benchmark script, you can email me at the email address provided above. No support, of course. :P

include

Example 7.5. Basic include() example

Example 7.6. Including within functions

Example 7.7. include() through HTTP

Example 7.8. Comparing return value of include

Example 7.9. include() and the return() statement

Example 7.10. Using output buffering to include a PHP file into a string

Related Examples ( Source code ) » include

Code Examples / Notes » include

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