php Class calling a function inside another function error - php

Question

I have the following class with few functions inside. I'm getting an error when i call the get_dir_size() inside the Diskspace() function. It's not recognizing it. What am i doing wrong. This code is for creating an expressionengine plugin.
Fatal error: Call to undefined function get_dir_size()
class DiskSpace
{
public $return_data = "";
public function Diskspace()
{
$this->EE =& get_instance();
$dir_name = $_SERVER['DOCUMENT_ROOT']."/userfiles/";
/* 1048576 bytes == 1MB */
$total_size= round((get_dir_size($dir_name) / 1048576),2) ;
$this->return_data = $total_size;
}
public function get_dir_size($dir_name){
$dir_size =0;
if (is_dir($dir_name)) {
if ($dh = opendir($dir_name)) {
while (($file = readdir($dh)) !== false) {
if($file !="." && $file != ".."){
if(is_file($dir_name."/".$file)){
$dir_size += filesize($dir_name."/".$file);
}
/* check for any new directory inside this directory */
if(is_dir($dir_name."/".$file)){
$dir_size += get_dir_size($dir_name."/".$file);
}
}
}
}
}
closedir($dh);
return $dir_size;
}
}

Answer 1

Change the line that calls get_dir_size($dir_name) to :-
$total_size= round(($this->get_dir_size($dir_name) / 1048576),2) ;
There are a few more issues with this code
What is this ? $this->EE = & get_instance();
and also you will get errors when you execute closedir($dh); if the if statement that it is declared in is not executed.

Answer 2

Remember when you call objects own function inside the object, use the $this pointer variable.
$total_size= round((get_dir_size($dir_name) / 1048576),2) ;
Change to
$total_size= round(($this->get_dir_size($dir_name) / 1048576),2) ;
Would be also good if you told us which line the error is happening at. Would be also nice to see the full error log.