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mmvergara
mmvergara

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The Array Way to Swap Variable - js,py and etc. i think.

#javascript #python #swap

This will pretty much will work in any data types im assuming?

let a = 'a1'
let b = 'b1'

a = [a,b]
b = a[0]
a = a[1]

console.log(a,b) // b1,a1
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a = 'a1'
b = 'b1'

a = [a,b]
b = a[0]
a = a[1]

print(a,b) # b1,a1
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There are better ways like, destructuring, this is just an alternative

Top comments (8)

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fjones profile image
FJones •

As a code golf answer, this can be done better, as a lot of languages now support some form of destructuring.

let a = 1, b = 2;
[b, a] = [a, b];
console.log(a, b);
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$a = 1; $b = 2;
[$b, $a] = [$a, $b];
echo $a.$b;
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a = 1
b = 2
[b, a] = [a, b]
print (a, b)
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mmvergara profile image
mmvergara •

yeah we probably all know this. im just sharing this alternative. do you know about which one is faster or like takes less memory? im genuinely curious

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fjones profile image
FJones •

Should be faster with my solution compared to yours, but slightly heavier on memory.

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joelbonetr profile image
JoelBonetR 🥇 •

10/10
Didn't thought on that one! 😂

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joelbonetr profile image
JoelBonetR 🥇 • • Edited

Yes it will work in most languages, it's the same from the behaviour point of view than doing:

let a = 1, b = 2;
let c = a;

a = b;
b = c;
// set c = undefined or let the GC do its thing
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But the memory footprint is higher using arrays plus the JIT will translate the code above to something like

let a=2, b=1;
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Either way I never needed to do such thing in real projects, just in college exercises a decade ago😅

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fjones profile image
FJones •

It has some applications in hashing and cryptography, to be fair. Rapid shifting of multiple values between variables. Though there's certainly easier (faster, and more lightweight) ways to achieve that.

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mmvergara profile image
mmvergara •

Yeah i agree, I just thought of sharing it, when I ask people in my campus they are always saying use the + - method which only works on ints. goodness.

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redhap profile image
HAP •

Suddenly, a integer-only solution appears that doesn't use an array/tuple. 'Tis a fun little value exchange routine w/o a third variable. Not useful, but fun.

# python
a = 1
b = 2
a = a + b
b = a - b
a = a - b
print(a, b)  # 2 1
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# bash
a=1
b=2
a=$(( $a + $b ))
b=$(( $a - $b ))
a=$(( $a - $b ))
echo "$a $b"
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