How are algebraic data types stored?

Question

C++ / C#

I read several articles on Habré, but they are all with a bias in Haskell. I can't figure out how algebraic data types are stored. Here is a piece of C++ code about it.

template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;

using var_t = std::variant<int, long, double, std::string>;
std::vector<var_t> vec = {10, 15l, 1.5, "hello"};

for (auto& v: vec) {
    std::visit(overloaded {
        [](auto arg) { std::cout << arg << ' '; },
        [](double arg) { std::cout << std::fixed << arg << ' '; },
        [](const std::string& arg) { std::cout << std::quoted(arg) << ' '; },
    }, v);
}

As I understand it, some kind of container (variable) is created in which pointers to elements in the heap are placed, which can be predefined types (otherwise - an error). I understand correctly?

Answer 1

en.cppreference.com/w/cpp/utility/variant
At the same time
en.cppreference.com/w/cpp/container/vector
This all means that all memory is allocated only in one place, the elements are stored by themselves, and not by pointers.