swapping two variables using bitwise opeation and not using a third variable in c

Question

i could do with third variable

c=a|b;
a=c&a;
b=c&a;

But i need to do it without third variable. I tried using XOR it wasn't helping me either.

Xor swap algo: http://en.wikipedia.org/wiki/XOR_swap_algorithm — Shafik Yaghmour, Jul 24 '13 at 14:10
Or perhaps: http://stackoverflow.com/questions/249423/how-does-xor-variable-swapping-work — Bill Lynch, Jul 24 '13 at 14:17

score 9 · Answer 1 · answered Jul 24 '13 at 14:10

9

it's an easy 1st year programming class question:

a = a^b;
b = a^b;
a = a^b;

answered Jul 24 '13 at 14:10

No Idea For Name

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score 6 · Answer 2 · answered Jul 24 '13 at 14:23

XOR has a property that XORing something twice always brings you back to where you started. You can use this fact to switch variables in three assignments without a third variable.

int a = 54;
int b = 23;

a = a XOR b; // (a XOR b)
b = a XOR b; // (a XOR b) XOR b = a
a = a XOR b; // (a XOR b) XOR a = b

swapping two variables using bitwise opeation and not using a third variable in c

2 Answers2