Finding the answer to this is turning out to be much more difficult than I would have thought. Since I don't have a clue what you'd call this, it's hard to run a Google search since it will ignore those characters.
I tried browsing the PHP Assignment Operators page, and even the other operators pages, and found nothing that told me exactly what they do. I don't just want to guess based on the single function I have that uses it. So what exactly do the '&=' and '=&' operators do?
All I know is it sets a variable, which would be the '=' part, so I really need to know what the '&' part is doing.
Please don't say the obvious; I need someone to explain exactly what they do. I know one of them is 'bitwise', but that doesn't mean anything to me.
$a = 1;
$b =& $a;
$a++;
echo $b; // 2
From PHP Manual on References:
References in PHP are a means to access the same variable content by different names.
&= is a bitwise AND assignment
$a = 1;
$a &= 1; // is the same as
$a = $a & 1;
echo $a; // 1
From Wikipedia on Bitwise AND:
A bitwise AND takes two binary representations of equal length and performs the logical AND operation on each pair of corresponding bits. In each pair, the result is 1 if the first bit is 1 AND the second bit is 1. Otherwise, the result is 0. For example:
0101
AND 0011
= 0001
EDIT: For a practical example on bitwise operations, see my answer to Bitwise Operations in PHP