What is ( ) in php?

Question

I’m making a comparison of two binary numbers by checking which index from right to left bits are different. I found a code as soon as it works:

strspn(strrev("1111") ^ strrev("1101"), "\0");

This code returns to me 1which is the index of the first bit of the numbers which are different. However I did not understand "bulhufas" of the code nor what that means: (^). I tried searching in the manual itself and did not find. To try to figure out what this is, I did this:

var_dump("aaab" ^ "aaac");

Only it returns a "string" of control character SOH.

So my question boils down to three parts:

1. What is this sign ( ) and what it does exactly?
2. How that first line of code works?
3. Because this return in control character SOH?

Answer 1

It is the XOR operator, as can be checked in more detail through this link: http://php.net/manual/en/language.operators.bitwise.php