Swap 2 integers without using a temp variable

There are 2 ways to do it. 

1. use sum of the 2 variables:

 void swap(int a, int b) {

       a = a + b;

       b = a - b;

       a = a - b

    }

     2. use bitwise operation (xor)

void swap(int a, int b) {

      a = a ^ b;

      b = a ^ b;

      a = a ^ b;

    }