iterate_through_storage.cpp

using storage_type = typename entt::storage_traits<entt::entity, MyComponent::storage_type;

storage_type::const_iterable g_iterable;
storage_type::const_iterable::const_iterator g_iterator;

extern "C" void setup ()
{
    const auto& storage = registry.storage<MyComponent>();
    g_iterable = storage.each();
    g_iterator = g_iterable.begin();
}

extern "C" std::uint32_t get_next (const MyComponent** component)
{
    if (g_iterator != g_iterable.end()) {
        const auto&& [entity, comp] = *g_iterator;
        ++g_iterator;
        *component = &comp;
        return static_cast<std::uint32_t>(entity);
    } else {
        *component = nullptr;
        return static_cast<std::uint32_t>(entt::entity{entt::null});
    }
}