serialize int to vector of bytes using std::vector::reverse_iterator?

Question

Next function works fine:

std::vector<uint8_t> serialize_bytes(uint32_t ui)
{
    return {(uint8_t*)&ui, (uint8_t*)(&ui+1)};
}

But its result depends on endianess of machine.

I also need to serialize bytes in reverse order:

std::vector<uint8_t> serialize_bytes(uint32_t ui)
{
    std::vector<uint8_t>::reverse_iterator 
        begin{(uint8_t*)(&ui+1)-1}
      , end{(uint8_t*)(&ui)-1};  //ERROR: Calling a private constructor
    return {begin, end};
}

I know multiple other ways to do serialization. The interest of this Q is to construct reverse_iterator from pointer in manner like first snippet does.

Answer 1

std::vector<uint8_t>::reverse_iterator can only point to elements of a std::vector<uint8_t> .

Use std::reverse_iterator<uint8_t *> :

std::vector<uint8_t> serialize_bytes(uint32_t ui)
{
    using iter_t = std::reverse_iterator<std::uint8_t *>;
    std::uint8_t *ptr = reinterpret_cast<std::uint8_t *>(&ui);
    return {iter_t(ptr + sizeof ui), iter_t(ptr)};
}

Answer 2

You can use std::reverse to help you with your task.

std::vector<uint8_t> serialize_bytes(uint32_t ui)
{
    std::vector<uint8_t> v{(uint8_t*)&ui, (uint8_t*)(&ui+1)};
    std::reverse(v.begin(), v.end());
    return v;
}

Answer 3

I took the above idea and rewrite it in own manner

std::vector<uint8_t> serialize_bytes(uint32_t ui)
{
    std::reverse_iterator<uint8_t*> begin{(uint8_t*)(&ui+1)}, end{(uint8_t*)(&ui)};
    return {begin, end};
}

thank you @HolyBlackCat