[Solved] How to swap two variables using bitwise operators (not XOR, and without temporary var) [closed]

Question

XOR, p ^ q, can be expressed using the and (&), or (|), and not/invert (~) bitwise operators as (p & q) | ~(p & q) (see Wikipedia’s exclusive or article). Hence, we can now simulate an XOR with the other bitwise operators to do the usual swap.

int x = 1;
int y = 2;
x = (x & y) | ~(x & y);
y = (y & x) | ~(y & x);
x = (x & y) | ~(x & y);

Although note Java will create temporary variables to store the intermediate values in the expression (eg. the results of x & y), so in practice or on real architectures this is slower than just storing a variable in a temporary, but from a theory perspective it may satisfy your question.

Note that @ytoamn’s answer is a better solution than mine as the JVM wouldn’t need to create extra temporary variables to store intermediate parts of expressions. (And isn’t just an XOR workaround)

Accepted Answer

XOR, p ^ q, can be expressed using the and (&), or (|), and not/invert (~) bitwise operators as (p & q) | ~(p & q) (see Wikipedia’s exclusive or article). Hence, we can now simulate an XOR with the other bitwise operators to do the usual swap.

int x = 1;
int y = 2;
x = (x & y) | ~(x & y);
y = (y & x) | ~(y & x);
x = (x & y) | ~(x & y);

Although note Java will create temporary variables to store the intermediate values in the expression (eg. the results of x & y), so in practice or on real architectures this is slower than just storing a variable in a temporary, but from a theory perspective it may satisfy your question.

Note that @ytoamn’s answer is a better solution than mine as the JVM wouldn’t need to create extra temporary variables to store intermediate parts of expressions. (And isn’t just an XOR workaround)