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

a += 2; is the equivalent of a = a + 2;

At one time with some languages (especially very old C compilers), the compiler produced better code with the first option. It sticks around now because it's a common idiom and people used to it think it's clearer.