PHP include absolute path

You can't include php files relatively to your webroot that way, cause if you use the slash as first character, the reference will go much deeper than just your document root. So, instead of using your basepath, you could do something like this :

<?php 
   $path = $_SERVER['DOCUMENT_ROOT'];
   $path .= "/yourpath/yourfile.php";
   include_once($path);
?>

If your server doesn't populate the "document_root", you may need this

    require(str_repeat('../',(substr_count(getenv('SCRIPT_URL'),'/')-1))."/path/to/file.php");

I use this line of code. It goes back to the "top" of the site tree, then goes to the file desired.
For example, let's say i have this file tree:
domain.com/aaa/index.php
domain.com/bbb/ccc/ddd/index.php
domain.com/_resources/functions.php

I can include the functions.php file from wherever i am, just by copy pasting

require(str_repeat('../',(substr_count(getenv('SCRIPT_URL'),'/')-1))."/_resources/functions.php");

If you need to use this code many times, you may create a function that returns the "str_repeat('../',(substr_count(getenv('SCRIPT_URL'),'/')-1))" part. Then just insert this function in the first file you include. I have an "initialize.php" file that i include at the very top of each php page and which contains this function. The next time i have to include files, i in fact just use the function (named "path_back"):

require(path_back()."/_resources/another_php_file.php");