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

There are lots of these shorthand operators in C, C++ in other modern languages.

a -= b;   // a = a - b;
a *= b;   // a = a * b;
a &= b;   // a = a & b;

etc., etc., etc.

Answer 2

$time += $diff['hours'];

is the same as saying

$time = $time + $diff['hours'];

Answer 3

Shortcut operator for $val = $val + $otherval.

This only works on numeric values

Answer 4

Also, "a += b" is an expression who's value can be used again immediately,

(((((a += b) *= c) += d) * e) += f);

is a lot less typing than

a = a + b;
a = a * c;
a = a + d;
a = a * e;
a = a + f;

Answer 5

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.