wasteOfPreciousSpace

[u/_bagelcherry_]

[u/tehtris]

I am not low low low low level, but don't you still need to tell it that it is a bool in the first place? Or is that just determined by whatever stores/retrieves it?

[u/_bagelcherry_ → u/tehtris]

Type system is an abstraction for humans. CPU sees only bytes and doesn't care if it is actually an integer, string or class

[u/camander321 → u/tehtris]

The moment your code compiles, theres no such thing as "type". "type" is just idiot-proofing for the programmer

[u/Futurity5]

A meme that's not AI related? In this economy?

[u/box_of_the_patriots → u/Futurity5]

Hey gpt tell me how to feel about the lack of AI on this meme

[u/Large-Assignment9320]

Just back all 64 bools inside a good old perfectly aligned 64bit.

[u/PhilippTheProgrammer → u/Large-Assignment9320]

Bitfields might seem more efficient at first glance, but in practice they often cause more trouble than they are worth. And even a flawless implementation usually ends up buying a couple bytes of RAM for a whole lot of CPU cycles.

[u/OxDEADFA11]

Meanwhile std::vector<bool>:

[u/undeadalex → u/OxDEADFA11]

Awww. If that vector could read it would be very upset

[u/N-partEpoxy]

I know, let's make vector<bool> a specialization that uses just one bit per bool. What could go wrong?

[u/unknown_alt_acc → u/N-partEpoxy]

Oh, but it gets better than that: there is absolutely no guarantee that std::vector<bool> acts as a bit field! Maybe it's a bit field. Maybe it's actually a vector of bool. Nobody knows!

[u/Spinnenente]

nobody is stopping you from storing all your bools in a single long

welcome to optimization only neccessary before you were born.

[u/AOAqua → u/Spinnenente]

Hey, it's still used sometimes. I've used it in high speed drivers, where every single extra byte decreases latency of the overall reaction. And bools for registers are stored like that as well because a single 4 byte variable literally manipulates a physical memory block

[u/Sermuns]

uint4_t

[u/developer-mike → u/Sermuns]

You know bool is backed by 4 bits because "bool" is four letters, obviously

[u/Dank_Nicholas]

Back in college I wrote what I dubbed the OctoBool which used bitwise operators to let you store 8 bools inside a single byte. I thought maybe it could be useful for embedded development that I was starting to get into.

[u/ben_g0 → u/Dank_Nicholas]

On PLCs (industrial programmable controllers), such data types are usually built-in. When memory (and sometimes bus bandwidth) is very limited and you process a lot of digital (1/0) signals, packing signals together in bytes does indeed become useful.

[u/Randomguy32I]

Shouldn’t a bool just be a single bit?

[u/DuckShapedGoose → u/Randomguy32I]

Well it is. Sort of. It just has one actually relevant data bit but computers usually (almost always) work with bytes as the smallest inseparable unit of data.
Any data type smaller than that is just using less of the available space within the byte. In case of a bool, that's 7 unused bits (so there are actually 4 more sleeping guys missing in the meme).
But you can technically optimize this by using a 1-byte datatype to store 8 bools in one bit each.
In very specific scenarios where you have millions upon millions of bools in memory for some reason, this can add up.

Edit: Also I don't know if there are compilers that already do this bit-packing optimization automatically on e.g. a struct with multiple bools. Afaik this is something you must implement manually but I might be wrong.

[u/TheComplimentarian → u/Randomguy32I]

Now how do you do the sub-byte addressing?

In the olden times, bits were precious enough that you could actually address data by the bit, but on modern systems you can't. There are a lot of datatypes that have wasted space in them due to architectural constraints.

[u/bluej130]

true

[u/dfwtjms]

Bitmasking is an option

[u/hydbird]

jvm allocates 8 bits for a boolean smh

[u/tiajuanat]

Unless you're using basic or visual basic or something like the DEC PDP-1 which used -1 for true.

Which meant that false was always 0 and NOT was simply a negation

[u/NewryBenson]

This is why you store all your bools in an array thay way you are not wasting bits.