How to add two numbers without using ++ or + or another arithmetic operator

Question

How do I add two numbers without using ++ or + or any other arithmetic operator?

It was a question asked a long time ago in some campus interview. Anyway, today some

Answer 1

With given answers above, it can be done in single line code:

int add(int a, int b) {
    return (b == 0) ? a : add(a ^ b, (a & b) << 1);
}