<?php
function get_root_path()
{
	$s_real_path = realpath('./');
	$s_self_path = $_SERVER['PHP_SELF'];
	$s_self_path = substr($s_self_path, 0, strrpos($s_self_path, '/'));
	return substr($s_real_path, 0,strlen($s_real_path) - strlen($s_self_path));
}

echo get_root_path();
?>