Swapping integer values

This post will be really small, I would like to show how to swap two integer values without using additional variable. The example had been written on C++, but it can be implemented on almost all programming languages.
int a = 1;
int b = 3;

a = a + b;
b = a - b;
a = a - b;

// here "a" has 3 as value and "b" has 1 as value.