When would you swap two numbers without using a third variable?

Question

I have read several sources that discuss how to swap two numbers without using a third variable. These are a few of the most relevant:

• How do you swap two integer variables without using any if conditions, casting, or additional variables?
• Potential Problem in "Swapping values of two variables without using a third variable"
• Swap two integers without using a third variable
• http://www.geeksforgeeks.org/swap-two-numbers-without-using-temporary-variable/

I understand why it doesn't make sense to use the described methods in most cases: the code becomes cluttered and difficult to read and will usually execute more slowly than a solution utilizing a third "temp" variable. However, none of the questions I have found discuss any benefits of the two-variable methods in practice. Do they have any redeeming qualities or benefits(historical or contemporary), or are they only useful as obscure programming trivia?

Answer 1

At this point it's just a neat trick. Speed-wise if it makes sense though your compiler will recognize a normal swap and optimize it appropriately (but no guarantees that it will recognize weird xoring and optimize that appropriately).