std::array<bool, N> 은 비트를 다루도록 특수화 되어있지 않음

std::vector<bool>은 내부적으로 bitset처럼 다뤄지도록 템플릿 특수화가 되어있다.

std::vector<bool> - cppreference.com

std::vector - cppreference.com

 

그런데 std::array<bool, ...> 은 비트를 다루도록 템플릿 특수화가 되어있지 않다.

 

c++ - No class template specialization for array of bool? - Stack Overflow

No class template specialization for array of bool?

When std::vector was introduced, a specialization for bool was considered a good idea. Basically, at that time, the average computer had 4 MB of memory, so saving computer memory was quite important. Nowadays we just say "memory is cheap" (quote from Uncle Bob).

Later it turned out that this specialization creates more problems then it is worth.

The issue is that the address to one of the elements of such a vector is a complex object (it has to store information on which bit holds which value) compared to regular old-fashioned C-array bool a[].

Since compatibility must be retained, this specialization can't be dropped, but based on that lesson, the same approach was not applied to std::array.

Another reason is that std::array is supposed to be a C-array wrapper, so it must be as similar to bool a[N] as possible, and must produce the same machine code when used.

And the last thing, as Cody Gray points out in a comment under question, std::bitset is a constant size array of bits, so such functionality is already available (and can be used if needed).

 

개인적인 생각은 bool array의 비트 특수화가 필요하지 않았을 거 같은 것도 한 몫 한다고 본다. std::bitset이 이미 있으니 bit로 이용하고 싶다면 std::bitset을 이용하면 되니까.

std::bitset - cppreference.com

std::bitset - cppreference.com