Can an enum class be converted to the underlying type?

Question

Is there a way to convert an enum class field to the underlying type? I thought this would be automatic, but apparently not.

enum class my_field         


        

Answer 1

I find the following function underlying_cast useful when having to serialise enum values correctly.

namespace util
{

namespace detail
{
    template 
    using UnderlyingType = typename std::underlying_type::type;

    template 
    using EnumTypesOnly = typename std::enable_if::value, E>::type;

}   // namespace util.detail


template >
constexpr detail::UnderlyingType underlying_cast(E e) {
    return static_cast>(e);
}

}   // namespace util

enum SomeEnum : uint16_t { A, B };

void write(SomeEnum /*e*/) {
    std::cout << "SomeEnum!\n";
}

void write(uint16_t /*v*/) {
    std::cout << "uint16_t!\n";
}

int main(int argc, char* argv[]) {
    SomeEnum e = B;
    write(util::underlying_cast(e));
    return 0;
}