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require() entspricht im Wesentlichen include(), wirft aber im Fehlerfall einen E_ERROR Fehler. Es beendet also die Programmausführung während include() nur eine Warnung (E_WARNING) generiert und so die weitere Programmausführung gestattet.
Weitere Informationen hierzu finden Sie in der include()-Dokumentation.
Require is a really neat function, compared to include. You can use it for security purposes. For example, consider that you have a database that's based on simple text-files. Theoretically, someone could type in the URL of those text-files, and view them directly in their browser. This is as opposed to what you want: those files only to be viewable through your own PHP script. Otherwise, the data won't be properly formatted, or much worse, you won't be able to do a proper secure authorization or authentication. So, here's the trick. Rename your .txt files to .php files. The first line should be this...
require('this_file_does_not_exist_and_will_never_exist');
Then, after that first line, the rest of the file is your database information. If someone tries access the file directly, they'll get an error, and see no information (danged hackers!). But, your PHP script that displays the database file will know that this line is there. This is assuming that you reprogram your text-database, php-front-end to ignore the first line of files when reading data.
It's not encryption, but it's powerful security, quick and cheap, for custom-built databases.
If you want to get a parsed PHP file, e.g file.php contains echo 'ciao'; the function below will return you the output of file.php that is ciao
<?php
// file and get, if you need to include a file.php?query_string.
function pinclude($file, $type, $get = null) {
$p = explode('/', $file);
$file = end($p);
$dir = '';
$n = count($p) - 1;
for($i = 0; $i < $n; $i++)
$dir .= $p[$i] . '/';
if($get !== null) {
$tmp = $_GET; // back up
$_GET = array();
$get = explode('&', $get);
$n = count($get);
for($i = 0; $i < $n; $i++) {
if(strpos($get[$i], '=') === false)
$_GET[$get[$i]] = 1;
else {
list($name, $val) = explode('=', $get[$i], 2);
$_GET[$name] = $val;
}
}
}
ob_start();
chdir($dir);
require $file;
$out = ob_get_clean();
if($tmp)
$_GET = $tmp;
return $out;
}
$out = pinclude('./dir/yourfile.php', 'a=b&c=d&e');
echo $out;
// i'm sorry but i forgot post requests...
?>
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.
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.
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;
$UserClass->UserFunction();
?>
I'm wondering if there is a method for declaring class public/private/protected functions from inside a require/include...
Two functions to help:
<?php
function add_include_path ($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, $paths));
}
}
?>
re the comment by moazzamk at gmail dot com
As the manual states require and require_once as of PHP 4.02 no longer call the file if the line of code it is on should not be executed.
If you want to verify that a file can be included or required, the simplest solution I've found is just to check that the file exists.
<?php
if(file_exists($pageContentInc)){
require_once $pageContentInc;
}else{
$pageContentInc = "common/content_404.inc";
require_once $pageContentInc;
}
?>
Does it really need to be any harder than that?
I love php. But when file can't be included, 'require' or 'require_once' throw fatal error and halt the script, which is almost never desirable on a mission-critical production server. I think it may be better to use something like the following.
<?php
if (@include 'plan_A.php') {
// Plan A;
} elseif (@include 'plan_B.php') {
// Plan B;
} else {
// Hope never happens. If does, then Email the webmaster;
// Call 911, Medic, Fire, Police, the president;
// Change hard drive, server, hosting service;
}
?>
Or handle trouble first is you wish
<?php
if (!@include 'plan_A.php') {
// Someone has kidnapped/corrupted Plan_A.php;
// Email the webmaster;
// Change hard drive, server, hosting service;
} else {
// Plan A;
}
?>
require and include read the included files even if they are not executed in the code. You can use eval() to avoid this.
eval('require filename;');
I don't know if it's faster to have the files included the regular way or the eval way though (in other words, I haven't tested their efficiency). It will be great if someone can test which is better.
Discovered a bit of weird behavior yesterday involving require() (using PHP 5.2.3). If you use require() inside a function, the "globals" in the file will be local to the function. An example of this:
test.php:
<?php
function TestFunc()
{
require('test2.php');
echo "<pre>" . print_r($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
$GLOBALS["MyTestGlobal"] = Array();
?>
Remember, when using require that it is a statement, not a function. It's not necessary to write:
<?php
require('somefile.php');
?>
The following:
<?php
require 'somefile.php';
?>
Is preferred, it will prevent your peers from giving you a hard time and a trivial conversation about what require really is.
A note that drove me nuts for 2 days!
Be carfull if you have a newline or blank space befor your php tags in the included/required file it will read as html and outputed.
If your running your output through javascript string evaluations which would be sensitive to newlines/white spaces be carfull that the first chars in the file are the php tages eg <?php
// Looks like I might have a fix for some on the
// relative path issue.
if (!function_exists('bugFixRequirePath'))
{
function bugFixRequirePath($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 $stringNewPath;
}
}
}
require_once(bugFixRequirePath("../config.php"));
If you are experiencing a bug related to using relative paths with include or require, it may be related to a grandparent directory that is executable but not readable. It will cause __FILE__ to return a relative path instead of the full path which it is supposed to show. This manifests itself in interesting ways that can be seemingly unrelated. For instance, I discovered it using the Smarty {debug} command which failed to find its template due to this issue. Please see the following for more details:
http://bugs.php.net/bug.php?id=34552
http://shiftmanager.net/~kurt/test/
I have found a problem when I try to access a php file via require($class_directory)
// # $class_directory contain a long full path and dot into the last folder.
// # $class_directory = "/var/.../app/system/plugintoto_1.0/class_plugintoto_1.0.php";
// dot ('.') and minus ('-') are not accepted in require !
When using symbolic links with PHP, specify a dotslash './page.php' path to ensure that PHP is looking in the right directory with nested requires:
E.g. when the required actual page1.php contains other require statements to, say page2.php, PHP will search the path that the symbolic link points to, instead of the path where the symbolic link lives. To let PHP find the other page2.php in the path of the symbolic link, a require('./page2.php'); statement will solve the puzzle.
I have learnt to manipulate this code into an effecitve and easy to use form. I use it with require_once, but it could be used for require.
require_once($_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.
WARNING: Be absolutely sure that your include paths are relative or directory based and not http!!!
require("http://www.mydomain.com/somefile.php"); //WRONG!!
require("usr/mydomain/somefile.php"); //CORRECT!!
If you are intending to access local files and you accidentally use an http address, the request will probably work. However, this creates a wierd situation that can cause all sorts of bugs in your scripts and slow your code down.
The problem is that the include spawns off another php request, and is essentially requesting the file in the same a way a remote viewer would. So rather than including the intended php code, instead you get the processed output from that single file executed in its own private scope.
It's a simple mistake, but it can be an awful problem to debug.
Walker
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.
Something which may not be immediately obvious is that if you use double quotes on the filename, you can use variables to specify the filename, allowing you to do something like this:
<?php
$query = "SELECT filename FROM updates WHERE version>$current ORDER BY version";
$updateresult = mysql_query($query) or exit($query.'<br />'.mysql_error());
while ($updaterow = mysql_fetch_row($updateresult)) {
require "$updaterow[0]";
}
?>
Drop this in a script on a server and you can push updates to your clients. Obviously, make sure you only run scripts you want to.
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";
?>
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
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.
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.
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