将强类型枚举传递给函数

Question

I have got strongly typed enum.

enum class CustomCommand : unsigned char
{
    ENQ = 0x05,
    ACK = 0x06,
    NAK = 0x15,
};

And the function like:

void print_byte(unsigned char byte)
{
    cout << "Byte: " << byte << endl;
}

But when I call the function, GCC throw an error like:

/home/ser/QTProjects/SerialPort/main.cpp:27: error: cannot convert 'CustomCommand' to 'unsigned char' for argument '1' to 'void print_byte(unsigned char)'
     print_byte(CustomCommand::ACK);
                                  ^

Why I always need to manually cast CustomCommand enum when I gave it unsigned char type?

Answer 1

The purpose of the c++ type system is to help tired and ADHA programmers not to mix bool and pants. (or in this case CustomCommand and char)

You must try and pass the enum "object" around as long as possible and cast only at the last point of use. As an example you could overload the print_byte function:

void print_byte(CustomCommand  cmd)
 {
     std::cout << static_cast<unsigned char>(cmd);
 };