Add numbers from a loop?

I have this code:

if ($handle = opendir($referrals_url)) {
    while (false !== ($file = readdir($handle))) {
        if ($file != "." && $file != "..") {
            $file = ereg_replace('.php','', $file);
            echo count($_SESSION[''.$file.'_filecount']);
        }
    }
    closedir($handle);
}

Code (markup):

It all works fine. It is reading a directory and getting a number (that is associated with the directory) from a session.

Currently there are 3 folders with 3 numbers. 1, 5 and 7

How do I add those numbers together, so that the above code doesn't output: 157?

I want it to add them and output: 13.

 

$sum = 0;
settype($sum, "integer");
if ($handle = opendir($referrals_url)) {
    while (false !== ($file = readdir($handle))) {
        if ($file != "." && $file != "..") {
            $file = ereg_replace('.php','', $file);
            echo count($_SESSION[''.$file.'_filecount']);
            $sum = $sum + count($_SESSION[''.$file.'_filecount']);
        }
    }
    closedir($handle);
}

echo $sum;

PHP:

 

You da man!

Thanks heaps. I have been trying to work that out for HOURS.

I was starting to get a bit stroppy

Much appreciated