Swapping without extra variables

swap.c

// Sample answer for a quiz :)

swap (int &a, int &b)
{
	a = a ^ b;	// a'  = a  ^ b
	b = a ^ b;	// b'  = a' ^ b  = a ^ b ^ b = a
	a = a ^ b;	// a'' = a' ^ b' = a ^ b ^ a = b
}