Are you smart enough?

[Guv]

For some pairs of variables, Xor can be used to swap values.

A = A Xor B 
B = A Xor B '(A Xor B) Xor B = A
A = B Xor A 'A Xor (A Xor B) = B

I would not be sure that the above would work if A, B are different length or different types of variables.