c++ - 使用 print 函数输出重载的 << 运算符？

Question

我已经成功地重载了我认为称为插入运算符的“<<”运算符。我有一个打印函数，它打印卡片对象实例的信息，当使用运算符时如何调用这个打印函数

例子:

Card aCard("Spades",8);  //generates an 8 of spades card object

aCard.Print(); // prints the suit and value of card

cout << aCard << endl;  // will print something successfully but how can I get the same results as if I were to call the print function?

在我的实现文件 card.cpp 中，我重载了 << 以用于我的卡片类。

卡片.cpp

void Card::Print()
{
    std::cout << "Suit: "<< Suit << std::endl;
    std::cout << "Value:" << Value << std::endl;
}

std::ostream& operator<<(std::ostream &out, const Card &aCard)
{
    Print();//this causes an error in the program
}

卡片.h

class Card
{
public:       
    std::string Suit;
    int Value;

    Card(){};
    Card(std::string S, int V){Suit=S; Value=V};

    void Print();

    friend std::ostream& operator<<(std::ostream&, const Card&)
};

Answer 1

您只需要一种实现方式。您可以制作一个带有 ostream 的 Print 函数并执行所有打印逻辑，然后从 Print() 调用它和 operator<<

void Card::Print()
{
    Print(std::cout);
}

std::ostream& operator<<(std::ostream &out, const Card &aCard)
{
    Print(out);
}

void Card::Print(std::ostream &out)
{
    out << "Suit: "<< Suit << std::endl;
    out << "Value:" << Value << std::endl;
    return out;
}

或者你可以得到 operator<<包含打印逻辑并调用 operator<<来自 Print :

void Card::Print()
{
    std::cout << *this;
}

std::ostream& operator<<(std::ostream &out, const Card &aCard)
{
     out << "Suit: "<< Suit << std::endl;
     out << "Value:" << Value << std::endl;
     return out;
}