What does ^ mean in PHP?

Question

I came across this line of code in an application I am revising:

substr($sometext1 ^ $sometext2, 0, 512);

What does the ^ mean

Answer 1

In PHP, ^ means 'bitwise XOR'. Your code XORs together two strings, then returns at most the first 512 characters.

In other words it does this:

return (at most the first 512 characters of (someText1 XOR someText2))