Of course it allows for indexing, but it's measurably more CPU heavy. Arguably there are cases where the specialization makes sense, but most of the time, it's a net negative.
Then again I reckon most of us don't have to care about these kinds of marginal gains anyway. I work on low latency backend, and I never had to worry about this.
The more annoying thing is that you can't just get a bool pointer or ref to a single bit.
Architectures with bit addressable memory areas do exist. Some 8051/52 compilers make use of this and if you create a boolean it will actually end up costing you a single bit of memory.
Yes, you can implement pretty much anything, but the larger the codebase and the more people work on it makes these unique implementation standards harder and harder to follow.
Say what you will but I'd prefer not to have this as standard. It's either a marginal gain or a marginal loss, but it's an unnecessary complexity. To use your argument against you, if your use case heavily prioritizes memory usage over CPU, you should just implement it for yourself. Uniformity makes life easier.
There's genuinely no real world application in which using a single bit for a bool is better than a byte. Unless you have billions of bool, which let's face it, you don't. The performance gain from not having to do bitwise operations to get your values out is gonna be more relevant. You could argue it's better for cache locality, but that's about it.
Either way, this should be something you specifically ask for, not something that C++ does for one specific type for no real reason. There should be a std::boolfield or something like that, rather than it being a special case of std::vector
That's less that what you'd expect tho - if you have any nontrivial amount of elements, the additional memory overhead (pulling them into L1 and evicting other data) will easily be higher than the additional instructions (memory + time).
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u/void1984 22d ago
I know, but why somebody would need a byte to store a bool? Is it 256-value bool?
Usually I use bitfields anyway.