Let a and b be the two variables.
// Swap a and b
a = a + b;
b = a - b;
a = a - b;
Example
Assume a =12, b =7
a = a + b; // a =19, b =7
b = a - b; // a =19, b =12
a = a - b; // a =7, b =12
But you should use a third variable when swapping. The above method fails when a and b are float or double. Also it cannot swap values whose addition is more that the max supported value. i.e. a + b > Int.Max for int type.
