// Basic conversions to/from strings and the underlying integral type. #include #include ENUM(Channel, uint8_t, Red, Green = 2, Blue, Alias = Red); void print_channel(Channel channel) { std::cout << "channel \'" << channel.to_string() << "\' has value " << (int)channel.to_integral() << std::endl; } int main() { // A value must be assigned upon construction. Channel channel = Channel::Green; print_channel(channel); // This will not work. // Channel default_constructed_channel; // Conversions from strings and the integral type. Function names are // prefixed with _ to avoid conflicts with constant names. _from_integral is // a checked cast. channel = Channel::_from_integral(0); print_channel(channel); channel = Channel::_from_string("Blue"); print_channel(channel); channel = Channel::_from_string_nocase("bluE"); print_channel(channel); // Bad conversions. try { channel = Channel::_from_integral(15); throw std::logic_error("expected an exception"); } catch (const std::runtime_error &e) { } try { channel = Channel::_from_string("Purple"); throw std::logic_error("expected an exception"); } catch (const std::runtime_error &e) { } try { channel = Channel::_from_string_nocase("bluee"); throw std::logic_error("expected an exception"); } catch (const std::runtime_error &e) { } // Unsafe unchecked cast. channel = Channel::_from_integral_unchecked(2); // Direct conversion of a constant unfortunately requires an explicit // promotion. std::cout << (+Channel::Green).to_string() << std::endl; // The type name is available as a string. std::cout << Channel::_name << std::endl; return 0; } static_assert(sizeof(Channel) == sizeof(uint8_t), "enum has the same size as its underlying integral type"); static_assert(alignof(Channel) == alignof(uint8_t), "enum has the same alignment as its underlying integral type"); static_assert(std::is_same(), "the underlying integral type is accessible as a member");