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submitted 9 months ago* (last edited 9 months ago) by Ategon@programming.dev to c/advent_of_code@programming.dev

Day 15: Lens Library

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FAQ


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[-] sjmulder 2 points 9 months ago

That array initialisation is pure poetry! ๐Ÿ˜„

[-] lwhjp 2 points 9 months ago

I'm not fluent in Rust, but is this something like the C++ placement new? Presumably just declaring a table of Vecs won't automatically call the default constructor? (Sorry for my total ignorance -- pointers to appropriate reading material appreciated)

[-] Gobbel2000@feddit.de 1 points 9 months ago

You can create an array filled with all the same values in Rust, but only if all values have the same memory representation because they will be copied. That just doesn't work with Vec's, because they must all have their own unique pointer. And to have uninitialized values at first (think NULL-pointers for every Vec) while creating each Vec, something like this is apparently needed.

The appropriate way would certainly have been to store the map as a Vec> instead of an array, but I just wanted to see if could.

[-] lwhjp 1 points 9 months ago

Ah, I see! Thank you.

this post was submitted on 15 Dec 2023
14 points (93.8% liked)

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