重载<<<运算符错误C2804:二进制'运算符<<'参数太多了

时间:2013-04-03 02:37:13

标签: c++ class operator-overloading

这是我的班级:

#ifndef CLOCK_H
#define CLOCK_H
using namespace std;

class Clock
{
    //Member Variables

    private: int hours, minutes;

    void fixTime( );

    public:
        //Getter & settor methods.
        void setHours(int hrs); 
        int getHours() const;
        void setMinutes(int mins); 
        int getMinutes() const; 

        //Constructors
        Clock(); 
        Clock(int);
        Clock(int, int);
        //Copy Constructor
        Clock(const Clock &obj);
        //Overloaded operator functions
        void operator+(const Clock &hours);
        void operator+(int mins);
        void operator-(const Clock &hours);
        void operator-(int minutes1);
        ostream &operator<<(ostream &out, Clock &clockObj); //This however is my problem where i get the error C2804. Saying that it has to many parameters 
};
#endif

所有这个功能应该是在不同时间超出时钟的值。

2 个答案:

答案 0 :(得分:15)

ostream &operator<<(ostream &out, Clock &clockObj); 

应该是

friend ostream &operator<<(ostream& out, Clock &clockObj);    

在课堂外定义。

见这里:Should operator<< be implemented as a friend or as a member function?

答案 1 :(得分:10)

 ostream &operator<<(ostream &out, Clock &clockObj);

应该是

 friend ostream &operator<<(ostream &out, Clock &clockObj);

根据Stanley等人的C ++ Primer(第四版第514页):

  

当我们定义符合的输入或输出运算符时   iostream库的约定,我们必须使它成为非成员   运营商。我们不能让运算符成为我们自己的类的成员。要是我们   那么,左手操作数必须是我们的对象   班级类型

因此,最好将<<>>重载为该类的朋友函数。