https://garrit.xyz/posts/2022-03-24-swapping-numbers-without-temp

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Swapping two Numbers without Temporary Variables

Mar 24 2022

Ever wondered how to swap two numbers without using a temporary
variable?

I just found this very old note that I thought is worth sharing. The
trick is quite old and you might already know about this, but when I
started out with programming, it blew my mind.

In school, we get taught to use a temporary variable to swap two
numbers:

let a = 5;
let b = 10;

let temp = a;

a = b;    // a = 10
b = temp; // b = 5

But by using some arithmetic, we can save us a few bytes of memory:

let a = 5
let b = 10

a = a + b // a = 15 ; b = 10
b = a - b // a = 15 ; b = 5
a = a - b // a = 10 ; b = 5

Please never use this in any production code. The less we have to
think about a piece of code, the better it is. It's a fun thought
experiment nevertheless!

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Written By: Garrit Franke

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