Question

我已成功重载'＆lt;＆lt;＆lt;我认为运算符被称为插入运算符。我有一个打印功能，打印卡对象实例的信息，如何在使用操作符时调用此打印功能

示例：

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?

在我的实施文件card.cpp中，我重载了＆lt;＆lt;用于我的卡类。

Card.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
}

Card.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

您只想要一个实现。您可以制作一个需要ostream的打印功能并执行所有打印逻辑，然后从Print()和operator<<

调用它

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;
}

或者您可以让operator<<包含打印逻辑并从operator<<致电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;
}

Answer 2

aCard.Print()而非operator<<

需要Print()

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

你没有说出错误是什么，但基本上你是在调用一个全局定义的Print()函数或一个与你的代码不存在的函数。

使用print函数输出重载＆lt;＆lt;运营商？

2 个答案: