Jason Novinger ( jnovinger@programming.dev ) M to Python@programming.dev · 3 years ago[Meme] Swapping integers in Pythonlemmy.worldimagemessage-square17linkfedilinkarrow-up137file-textcross-posted to: bumba@boomer.casinoprogrammerhumor@lemmy.ml
arrow-up137image[Meme] Swapping integers in Pythonlemmy.worldJason Novinger ( jnovinger@programming.dev ) M to Python@programming.dev · 3 years agomessage-square17linkfedilinkfile-textcross-posted to: bumba@boomer.casinoprogrammerhumor@lemmy.ml
minus-squaredmad ( dmad@programming.dev ) linkfedilinkarrow-up5·3 years agoxor has the property x ^ x = 0, and x ^ 0 = x. So, x ^ x ^ y = y a' = a ^ b b' = b ^ a' = b ^ (a ^ b) = a a'' = (a ^ b) ^ a = b This is pretty clever, I’ve never seen this for a swap.
minus-squareActuallyRuben ( ActuallyRuben@actuallyruben.nl ) linkfedilinkarrow-up2·3 years agoCouldn’t have explained it better myself. I don’t remember where exactly I first read about this trick, but it’s mainly useful in C or Assembly, as you don’t have to resort to using a third variable/register.
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xor has the property x ^ x = 0, and x ^ 0 = x. So, x ^ x ^ y = y
a' = a ^ b b' = b ^ a' = b ^ (a ^ b) = a a'' = (a ^ b) ^ a = bThis is pretty clever, I’ve never seen this for a swap.
Couldn’t have explained it better myself. I don’t remember where exactly I first read about this trick, but it’s mainly useful in C or Assembly, as you don’t have to resort to using a third variable/register.