Need to convert std::vector<ButtonElement> buttonList to std::vector<BYTE> byteVector

Question

I need to convert std::vector buttonList to std::vector byteVector. I did it using this memcpy(&byteVector, &buttonList, buttonList.size() * sizeof(TenderButtonList_Element));

But one of my seniors mentioned that it is not proper usage of STL but didn't say exactly what it is. I suspect that memcpy should not be used on vectors. Is the above conversion valid, I observed that it served its purpose but wanted to know if it is valid or not. If it isn't, can you point the correct way.

Answer 1

If it isn't, can you point the correct way.

That depends on what you are trying to accomplish.

You have a sequence (a vector ) of TenderButtonList_Element , right?

You're looking to produce a sequence of bytes containing the same bit pattern as the first sequence? Is that correct?

If that is what you're after, then you want something like this:

vector<std::byte> vBytes;
vBytes.resize(buttonList.size() * sizeof(TenderButtonList_Element));
memcpy(vBytes.data(), buttonList.data(), vBytes.size());

If you want something else, then you'll need to say what that is.

Note that, in general, memcpy -ing c++ objects around does not produce valid objects.