[xpi0t0s]

Quote:

Originally Posted by SaswatPadhi

Or in a single line :

a^=b^=a^=b;

This code has undefined behavior, since it modifies the lvalue a twice without an intervening sequence point.

See http://en.wikipedia.org/wiki/XOR_swap_algorithm

The "Reasons for avoidance in practice" part is also worth a read.