How to swap variables without using another space?

http://www.tekpool.com/node/2694

This is a very common interview question which is very useful for practical programming paradigm.

void swap (int &i, int &j) {

i = i ^ j;

j = j ^ i;

i = i ^ j;

}

Or define a MACRO:

#define SWAP(i, j) (((i) ^= (j)), ((j) ^= (i)), ((i) ^= (j)))