What does the |= operator do?

Question

I saw this operator |= in another question and I wondered what it does. It looks like this:

 $result |= (ord($safe[$i % $safeLen]) ^ ord($user[$i]));

Answer 1

It's just a combined operator: assignment(=) and a OR operator(|). It's the same as:

$result = $result | (ord($safe[$i % $safeLen]) ^ ord($user[$i]));

Bitwise OR(inclusive) operator |:

  a  |  b  |  result
---------------------
  0  |  0  |   0
  1  |  0  |   1
  0  |  1  |   1
  1  |  1  |   1

Bitwise XOR(exclusive) operator ^:

  a  |  b  |  result
---------------------
  0  |  0  |   0
  1  |  0  |   1
  0  |  1  |   1
  1  |  1  |   0