访问类C++的私有变量

Question

试图重载==操作符，想要比较小时，分钟，秒变量，但它们被声明为私有变量，并且我们被告知我们不允许调整标题文件。如何在我的代码中访问它们以重载==运算符？我也无法将它们作为h，m，s来访问，因为它们是在setTime方法中调用的。

// using _TIMEX_H_ since _TIME_H_ seems to be used by some C++ systems 

#ifndef _TIMEX_H_ 
#define _TIMEX_H_ 

using namespace std; 

#include <iostream> 

class Time 
{ public: 
    Time(); 
    Time(int h, int m = 0, int s = 0); 
    void setTime(int, int, int); 
    Time operator+(unsigned int) const; 
    Time& operator+=(unsigned int); 
    Time& operator++(); // postfix version 
    Time operator++(int); // prefix version 

    // new member functions that you have to implement 

    Time operator-(unsigned int) const; 
    Time& operator-=(unsigned int); 
    Time& operator--();  // postfix version 
    Time operator--(int); // prefix version 

    bool operator==(const Time&) const; 
    bool operator<(const Time&) const; 
    bool operator>(const Time&) const; 

    private: 
    int hour, min, sec; 

    friend ostream& operator<<(ostream&, const Time&); 

    // new friend functions that you have to implement 

    friend bool operator<=(const Time&, const Time&); 
    friend bool operator>=(const Time&, const Time&); 
    friend bool operator!=(const Time&, const Time&); 

    friend unsigned int operator-(const Time&, const Time&); 
}; 

#endif 

.cpp文件

using namespace std; 

#include <iostream> 
#include <iomanip> 
#include "Time.h" 

Time::Time() 
{ hour = min = sec = 0; 
} 

Time::Time(int h, int m, int s) 
{ setTime(h, m, s); 
} 

void Time::setTime(int h, int m, int s) 
{ hour = (h>=0 && h<24) ? h : 0; 
    min = (m>=0 && m<60) ? m : 0; 
    sec = (s>=0 && s<60) ? s : 0; 
} 

Time operator==(Time &t1, Time &t2) 
{ 
    return (t1.hour==t2.hour); 
} 

Answer 1

你应该实现==运营商是一个成员函数，所以你应该定义

bool Time::operator==(const Time& t) const 
{ 
    return hour == t.hour && min == t.min && sec == t.sec; 
} 

Answer 2

这里有一个窍门：

bool operator==(Time &t1, Time &t2) 
{ 
    return !(t1 != t2); 
} 
bool operator!=(const Time& t1, const Time& t2) 
{ 
    return t1.hour != t2.hour || t1.min != t2.min || t1.sec != t2.sec; 
} 

你不能acc在您的运营商==功能中使用您的私人字段。但是因为你的操作符！=被定义为朋友，所以你可以在那里做。