this post was submitted on 01 Jan 2026
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Programming

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What are some cool and obscure data structure you know of? (programming.dev)
submitted 6 days ago by protein@programming.dev to c/programming@programming.dev
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[โ€“] anton@lemmy.blahaj.zone 1 points 3 days ago (1 children)

I came up with a kind of clever data type for storing short strings in a fixed size struct so they can be stored on the stack or inline without any allocations.

C++ already does that for short strings while seamlessly switching to allocation for long strings.

It's always null-terminated so it can be passed directly as a C-style string, but it also stores the string length without using any additional data (Getting the length would normally have to iterate to find the end).

Also the case in the standard library

The trick is to store the number of unused bytes in the last character of the buffer. When the string is full, there are 0 unused bytes and the size byte overlaps the null terminator.

Iirc, that trick was used in one implementation but discontinued because it was against the standard.

(Only works for strings < 256 chars excluding null byte)

If you need a niche for allocated string you can get to 254 but the typical choice seem to be around 16.

[โ€“] xthexder@l.sw0.com 1 points 3 days ago* (last edited 3 days ago)

C++ already does that for short strings

I've already been discussing this. Maybe read the rest of the thread.

Also the case in the standard library

I think you're missing the point of why. I built this to be a nearly drop in replacement for the standard string. If this wasn't the case it would need to do even more processing and work to pass the strings to anything.

discontinued because it was against the standard.

Standards don't matter for an internal type that's not exposed to public APIs. I'm not trying to be exactly compatible with everything under the sun. There's no undefined behavior here so it's fine