这是咋回事啊?友元函数和私有变量问题

2010-01-22 09:43:36 122 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

嵌入式人工智能（18-基于树莓派4B的继电器JQC-3FF-S-Z）本次实验的输出端控制不会接强电，就用LED灯来模拟即可，由于我那个流水灯模块是低电平点亮，所以接线稍有不同，同学们注意。只有继电器吸合，输出端的NO与COM就导通，给LED低电平然后就亮，否则继电器断开，NO与COM不导通，LED不亮。原理都一样，控制电流的接通与断开，这个模块看起来还简单点，毕竟还有2个指示灯，下端IN如接上电源红灯亮，继电器动作有电流通过绿灯亮。在实际应用中，可以通过编程控制继电器的通断状态，例如在Python编程中设置继电器模块的通断时间，从而实现自动化控制。阅读详情

代码如下:



#include <iostream>

#include <cctype>

#include <cstdlib>

//#include "dtime.h"

using namespace std;



class DigitalTime

{

    public:

        friend bool operator ==(const DigitalTime &time1,const DigitalTime& time2);

        DigitalTime(int the_hour,int the_minute);

        DigitalTime();

        void advance(int minutes_added);

        void advance(int hours_added,int minutes_added);

        friend istream& operator >>(istream& ins,DigitalTime the_object);

        friend ostream& operator <<(ostream& outs,const DigitalTime the_object);

    private:

        int hour;

        int minute;

};



void read_hour(istream& ins,int& the_hour);

void read_minute(istream& ins,int& the_minute);

bool operator ==(const DigitalTime& time1,const DigitalTime& time2)

{

    return (time1.hour==time2.hour && time2.minute==time2.minute);

}



DigitalTime::DigitalTime(int the_hour,int the_minute)

{

    if(the_hour<0 || the_minute<0)

    {

        cout<<"Illegal time!\n";

        system("pause");

        exit(1);

    }

    hour=the_hour;

    minute=the_minute;

}



DigitalTime::DigitalTime():hour(0),minute(0)

{}



void DigitalTime::advance(int hours_added,int minutes_added)

{

    int new_hours,new_minutes;

    new_minutes=minute+minutes_added;

    minute=new_minutes%60;

    new_hours=hour+hours_added+new_minutes/60;

    hour=new_hours%24;

}



void DigitalTime::advance(int minutes_added)

{

    int gross_minutes=minute+minutes_added;

    minute=gross_minutes%60;

    int hour_adjustment=gross_minutes/60+hour;

    hour=hour_adjustment%24;

}



ostream& operator <<(ostream& outs,const DigitalTime& the_object)

{

    outs<<the_object.hour<<":";

    if(the_object.minute<10)

    outs<<'0';

    outs<<the_object.minute;

    return outs;

}



istream& operator >>(istream& ins,DigitalTime& the_object)

{

    read_hour(ins,the_object.hour);

    read_minute(ins,the_object.minute);

    return ins;

}



int digit_to_int(char c)

{

    return (c-'0');

}



void read_hour(istream& ins,int& the_hour)

{

    char c1,c2;

    ins>> c1>>c2;

    if(!(isdigit(c1) && isdigit(c2) || c2==':'))

    {

        cout<<"Error illegal input to read_hour.\n";

        system("pause");

        exit(1);

    }

    if(c2==':')

    the_hour=digit_to_int(c1);

    else

    {

        the_hour=digit_to_int(c1)*10 + digit_to_int(c2);

        ins>>c2;

        if(c2!=':')

        {

        cout<<"Error illegal input to read_minute.\n";

        system("pause");

        exit(1);

        }

    }

    if(the_hour>24 || the_hour<0)

    {

        cout<<"Error illegal input to read_hour.\n";

        system("pause");

        exit(1);

    }

}



void read_minute(istream& ins,int& the_minute)

{

    char c1,c2;

    if(!isdigit(c1) || !isdigit(c2))

    {

        cout<<"Error illegal input to read_minute.\n";

        system("pause");

        exit(1);

    }

    the_minute=digit_to_int(c1)*10 + digit_to_int(c2);

    if(the_minute<0 || the_minute>60)

    {

        cout<<"Error illegal input to read_minute.\n";

        system("pause");

        exit(1);

    }

}

错误如下：

15 D:\dev\c++\dtime.h
`int DigitalTime::hour' is private
16 D:\dev\c++\dtime.h
`int DigitalTime::minute' is private

别的函数都可以访问私有变量，就
friend istream& operator >>(istream& ins,DigitalTime the_object);
friend ostream& operator <<(ostream& outs,const DigitalTime the_object);
这两个函数不行，实在是蹊跷，眼睛快看爆掉了也没看有出啥错误，各位帮帮忙

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