PHP require file from top directory

问题

I have several subdomains contained in their own directory above my root site, and an assets folder in my root directory. For example:

/
/assets/
/forums/
/blog/

I'm trying to require() files on php pages in both the root directory, and the subdirectories, for example, assets/include/form.php is required() in both index.php in the root directory and index.php in the forums directory. However, inside form.php, is another require, trying to get another file contained in the include directory.

I can't seem to find a way to require a file inside this form.php where it will work on both the root directory's index.php and the forum directory's index.php.

Is there any way I can explicitly require a file starting from the root directory?

回答1:

There are several ways to achieve this.

Use relative path from `form.php`

require_once __DIR__ . '/otherfile.php';

If you're using PHP 5.2 or older, you can use dirname(__FILE__) instead of __DIR__. Read more about magic constants here.

Use the `$_SERVER['DOCUMENT_ROOT']` variable

This is the absolute path to your document root: /var/www/example.org/ or C:\wamp\www\ on Windows.

The document root is the folder where your root level files are: http://example.org/index.php would be in $_SERVER['DOCUMENT_ROOT'] . '/index.php'

Usage: require_once $_SERVER['DOCUMENT_ROOT'] . '/include/otherfile.php';

Use an autoloader

This will probably be a bit overkill for your application if it's very simple.

Set up PHP's include paths

You can also set the directories where PHP will look for the files when you use require() or include(). Check out set_include_path() here.

Usage: require_once 'otherfile.php';

Note:

I see some answers suggest using the URL inside a require(). I would not suggest this as the PHP file would be parsed before it's included. This is okay for HTML files or PHP scripts which output HTML, but if you only have a class definition there, you would get a blank result.

回答2:

If one level higher use:

include('../header.php');

if two levels higher:

include('../../header.php');

Fore more, visit: http://forums.htmlhelp.com/index.php?showtopic=2922

回答3:

suppose you have pgm1.php in www.domain.com/dir1/dir2/dir3/pgm1.php, which include or require 'dirA/inc/Xpto.php'.
and another pgm2.php in www.domain.com/dirZ1/dirZ2/pgm2.php, which include or require same 'dirA/inc/Xpto.php'.
and your Host configuration not authorize require/include 'http://www.domain.com/......'
So...you can use this, in both pgm1.php & pgm1.php, and REQUIRE or
INCLUDE works !
```
function rURI($p){
   for($w='',$i=1;$i<(count(explode('/',$_SERVER['PHP_SELF']))-1);$i++,$w.='../');return
   $w.$p; }
```
require rURI('dirA/inc/Xpto.php'); // path from root

回答4:

You have 2 solutions. You can either use the full URL to the file, for instance if your file is in the 'lib' directory you can use: require_once ('http://www.example.com/lib/myfile.php')

You can try the $_SERVER['DOCUMENT_ROOT'] function in PHP but this isnt always fool proof.

回答5:

why don't you use (../)

require('../folder/file.php');

来源：https://stackoverflow.com/questions/7630002/php-require-file-from-top-directory

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