How to define a static array of std::byte in C++?

Question

I've got this long list of bytes (as in, they don't represent chars or int).
At the moment, I can just do the following:

static const char myArray[] = {0xb8, 0xfe, 0x6c, 0x39, 0x23, ...}

What I would like is to replace char with std::byte, but the compiler complains

a value of type "int" cannot be used to initialize an entity of type "const std::byte"

I've seen a couple of suggestions floating around, but I don't find any of them appropriate:

1. Wrap each byte in a std::byte() call.
   While that certainly is the easiest way to fix it, I hope we can appreciate how ridiculous that would look.
2. static const std::byte* myByteArray= reinterpret_cast<const std::byte*>(myArray);
   It's *a* solution, but I lose the ability to query the size (sizeof myByteArray) and I have to deal with an extra variable.
3. Using a variadic template function, as described in this answer
   This solution changes the data type I was working with. And maybe I'm just not experienced enough, but I don't trust std::array for defining static arrays.
4. User-defined literals.
   Similar to point (1), but shorter. I can overload _b and apply it to every element. This still leaves me wishing for a solution where I don't have to touch every item in the list.

I was also thinking about a variadic macro that could apply the byte constructor over each item, but macros can't be recursive and I don't know enough about them in the first place.

Is there anything I left out? Let me know if there is a good solution out there.

Answer 1

You could create a user defined literal operator e.g. (code link):

#include <cstddef>
#include <iostream>
#include <array>

constexpr std::byte operator""_b(unsigned long long int i){
    return static_cast<std::byte>(i);
}

static const std::array arr_cpp { 0xb8_b, 0xfe_b, 0x6c_b, 0x39_b, 0x23_b };

static const std::byte arr_c[] { 0xb8_b, 0xfe_b, 0x6c_b, 0x39_b, 0x23_b };

int main(){
    for(auto a : arr_cpp){
        std::cout << static_cast<int>(a) << "\n";
    }
    std::cout << "-----------\n";
    for(auto a : arr_c){
        std::cout << static_cast<int>(a) << "\n";
    }
   return 0; 
}

It doesn't really matter if you use pure c array or a wrapped c++ array - in c++ there is no constant conversion from int to std::byte or char.