How does the bitwise operator XOR ('^') work?

Question

I\'m a little confused when I see the output of following code:

$x = \"a\";
$y = \"b\";
$x ^= $y;
$y ^= $x;
$x ^= $y;
echo $x; //Got b
echo $y; //Got a
         


        

Answer 1

The ^ operator performs an XOR on the bit values of each variable. XOR does the following:

a   = 1100
b   = 1010
xor = 0110

x is the result of the XOR operation. If the bits are equal the result is 0 if they are different the result is 1.

In your example the ^= performs XOR and assignment, and you swap the bits around between the two variables $x and $y.

Read more here http://en.wikipedia.org/wiki/Xor_swap_algorithm