How to get the relative directory no matter from where it's included in PHP?

Question

If it's Path_To_DocumentRoot/a/b/c.php,should always be /a/b.

I use this:

dirname($_SERVER["PHP_SELF"])

But it won't work when it's included by another file in a different directory.

EDIT

I need a relative path to document root .It's used in web application.

I find there is another question with the same problem,but no accepted answer yet.

http://stackoverflow.com/questions/1240462/php-convert-file-system-path-to-url

Answer 1

PHP < 5.3:

dirname(__FILE__)

PHP >= 5.3:

__DIR__

EDIT:

Here is the code to get path of included file relative to the path of running php file:

    $thispath = explode('\\', str_replace('/','\\', dirname(__FILE__)));
    $rootpath = explode('\\', str_replace('/','\\', dirname($_SERVER["SCRIPT_FILENAME"])));
    $relpath = array();
    $dotted = 0;
    for ($i = 0; $i < count($rootpath); $i++) {
        if ($i >= count($thispath)) {
            $dotted++;
        }
        elseif ($thispath[$i] != $rootpath[$i]) {
            $relpath[] = $thispath[$i]; 
            $dotted++;
        }
    }
    print str_repeat('../', $dotted) . implode('/', array_merge($relpath, array_slice($thispath, count($rootpath))));

Answer 2

Do you have access to $_SERVER['SCRIPT_NAME']? If you do, doing:

dirname($_SERVER['SCRIPT_NAME']);

Should work. Otherwise do this:

In PHP < 5.3:

substr(dirname(__FILE__), strlen($_SERVER['DOCUMENT_ROOT']));

Or PHP >= 5.3:

substr(__DIR__, strlen($_SERVER['DOCUMENT_ROOT']));

---

You might need to realpath() and str_replace() all \ to / to make it fully portable, like this:

substr(str_replace('\\', '/', realpath(dirname(__FILE__))), strlen(str_replace('\\', '/', realpath($_SERVER['DOCUMENT_ROOT']))));