What is += used for?

Question

I think this is a dumb question but I could not find it on php. Why is a + with the = in the following code:

function calculateRanking()
{
    $created = $th         


        

Answer 1

According to your code

$time += $diff['hours'];
$time += ($diff['minutes'] / 60);
$time += (($diff['seconds'] / 60)/60);

are similar to the following:-

$time = $time + $diff['hours'];
$time = $time + ($diff['minutes'] / 60);
$time = $time + (($diff['seconds'] / 60)/60);