Swapping through shift operators ?

[Iftikhar Arain]

Can any one tell me how to swap two numbers without using third number with the help of shift operators.
Thanks

[Steve Morrow]

Swap using shift operators? No clue. The XOR swap is well-known, though...

http://en.wikipedia.org/wiki/Xor_swap_algorithm

Example:

int i = 5;
int j = 7;
 
System.out.println("i = " + i + "\nj = " + j); // 5, 7
 
i ^= j;
j ^= i;
i ^= j;
 
System.out.println("i = " + i + "\nj = " + j); // 7, 5

[ September 16, 2005: Message edited by: Steve Morrow ]

[Ulf Dittmer]

If you know that i and j are int (i.e., can be represented in 32 bits), something like the following would do the trick.

long i = 5;
int j = 7;

i = (i << 32) + j;
j = i >> 32;
i = i & 1111111111111111;

I haven't tested it, and it doesn't work with negative numbers, but you get the idea.

Of course, you can just use simple arithmetic:

i = i + j;
j = i - j;
i = i - j;