In a C++ quiz, we were asked to write a program to swap two integer variables without using a third temporary variable.
Any suggestions??
9  7787 
In a C++ quiz, we were asked to write a program to swap two integer variables without using a third temporary variable.
Any suggestions??
You can apply some logic like this:
b = a + b;
a = b - a;
b = b - a;
There may be other ways too.
Regards
Look up XOR swap.
I don't recommend using these swapping tricks though. The most optimal swapping algorithm is implicitly swapping the references to the variables, which a modern compiler will most likely do. You can't beat that with any gimmick you come up with.
Thank you very much but the one method which oler1s mentions, Does it use a temp var or not??
Well, what do you think, given that I was answering your question?
Plus, why didn't you actually look it up and see for yourself? You would know whether XOR swaps use temporary variables or not just by seeing the method online.
Please tone down. You have got me wrong. Thank you for the Swap Code . I got the code from the net. It works in the same way as the Add-swap does except it does the swap with bit operations.
Actually my query was about what you mentioned as ...
"The most optimal swapping algorithm is implicitly swapping the references to the variables, which a modern compiler will most likely do."
I would like you to focus on this point:there is not so much advantage in using XOR swap,consider this code written in MIPS/DLX assembly
[code]
lw $t1,BaseA(0) //we assume that our variables a,b are at postion
lw $t2,BaseB(0) // Mem[BaseA+0] and Mem[BaseB+0] respectively
so we could do something like this -
sw $t2,BaseC(0)
-
lw $t1,BaseC(0)
-
lw $t2,BaseA(0)
-
that is exactly the same number of istructions needed to do XOR Swap -
xor $t1,$t1,$t2
-
xor $t2,$t1,$t2
-
xor $t1,$t1,$t2
-
so I don't think XOR swap is so optimizing
Let's stick to C++ in this forum. MIPS/DLX is beyond me.
I'm sorry,you're right;let's stick to high level!
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