C ++ ostream运算符<<重载

Question

I have a Card with parameters (Color, Value) and method to output Card's parameters.

Error binary '<<' : no operator found which takes a right-hand operand of type 'CardColor' and 'CardValue'(or there is no acceptable conversion)

Card.h

struct Card{
    Color CardColor;
    Value CardValue;

    Card(Color color, Value cardValue) {
        this->CardColor = color;
        this->CardValue = cardValue;
    }
    public:
    friend std::ostream &operator<<(std::ostream &output, const Card c);
};

Value.h

#ifndef VALUE_H
#define VALUE_H
enum class Value{ SEDMA, OSMA, DEVITKA, DESITKA, SPODEK, KRAL, ESO, SVRSEK };
#endif

Color.h

#ifndef COLOR_H
#define COLOR_H
enum class Color { ZALUD, LISTY, SRDCE, KULE };
#endif

Main.cpp

#include <Card.h>
std::ostream &operator<<(std::ostream &output, const Card c)
{
    output << c.CardColor << c.CardValue << std::endl;
    return output;
}

void outputCard(Card c)
{
    std::cout << c << std::endl;
}

Answer 1

From you comment:

binary '<<' : no operator found which takes a right-hand operand of type 'CardColor' and 'CardValue' (or there is no acceptable conversion)

You also need to provide operator<< for the Color and Value class.

example of this for the Color class:

#ifndef COLOR_H
#define COLOR_H

#include <iostream>

enum class Color { ZALUD, LISTY, SRDCE, KULE };

inline std::ostream& operator<<(std::ostream& os, const Color& col)
{
    switch (col) {
      case ZALUD :
        os << "ZALUD";
        break;

      // ...
    }

    return os;
}

#endif