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# Can someone debug this for me?

var x = 0; for(; x <= 8; x++){ x += x - x++; console.log(x); } console.log("final value: ", x); //i found this in a javascript challenge

5/15/2022 2:09:31 PM

Harsha S

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I ran it on my pc, in vs code. It works fine. But I think the third line isn't doing much. When I comment it out, the result is the same.

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I think, it will be evaluated like x = x + ( x - x--) ; // the post increment here x-- is pushed into stack for evaluation separately.. then x = x + 1 is updated. But previous calculatuon x+( x- x--) is evaluated and result is stored in x so overrites x++ value with x +(x-x) which is just equalto x = x + ( x - x) ; So in loop, x value unchages.. Final value : 9 Hope it helps..

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Jayakrishna🇮🇳 thank you but I am not able to get it completely

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Paul that's interesting

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0 += 1-1 1 += 2-2 2 +=3-3 Basicaly you are doing x += 0

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Raul Ramirez how is it 1-1, 2-2, 3-3 and so on...?

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Cpu calculates right to left

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Because post increment, the value uses first in expression then increment So x - x++ is done like x - x, x++ x += x - x++ is done like x = ( x + ( x - x ) ), x++ x++ update x but it is overritten by value ( x + ( x - x)) which is actually equal to (x - 0) => x Instead of storing back in x , use any other variable, you can see x++ value . I thought, your doubt is in x += x - x-- result. Where you not understood my reply.. Tell about specific lines.. But hope it clears now..

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Thanks Jayakrishna🇮🇳 ! I got it now.

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Harsha S no but it does have an order of operations similar to it

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You're welcome..

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I use vscode to debug things, i hope this helps 🙂

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No error when i ran it

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Raul Ramirez yeah, right. i forgot that. but does it not follow BODMAS too?

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Dada Praise Oluwatomiwa so, how did you learn to copy paste?