Xor swap algorithm

Xor swap is a simple algorithm which uses the Exclusive disjunction (XOR) operation to swap the values of two variables without using an extra variable. This algorithm follows (where X and Y are the names of two variables, rather than two values):

1. XOR the values of X and Y and store the result in X
2. XOR the values of X and Y and store the result in Y
3. XOR the values of X and Y and store the result in X

To see how this works, call the initial value of X = x0 and the initial value of Y = y0. Then:

• after step 1, X = x0 XOR y0, Y = y0
• after step 2, X = x0 XOR y0, Y = x0 XOR y0 XOR y0 = x0
• after step 3, X = x0 XOR y0 XOR x0 = y0, Y = x0

This algorithm varies from other swap algorithms only in that it doesn't need to store the original value of X in a temporary buffer prior to overwriting it and doesn't need to restore this value in Y.

See: Assembler code, Visual Basic code, C code