不理解我收到的错误消息

Not understanding the error message I'm getting

本文关键字：错误 消息 不理解      更新时间：2023-10-16

我根据这本书做了一个朋友函数程序，我对程序做了一些我自己的代码。我很困惑，因为我收到此错误消息，指出"room_num"未声明，智能感知标识符"room_num"未定义。我需要帮助来理解为什么会发生这种情况以及如何解决它。这是我过去三周一直在处理的代码。

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

 using namespace std;
 class HotelRoom
{
friend int Transfer( HotelRoom&, int);
 private:
int room_num; 
int transroom_num;
int room_cap;
int occup_stat;
double daily_rt;

public:
HotelRoom(int room, int roomcap, int occup,  int transroom, double rate = 89.00);
~HotelRoom();
int Display_Number();  //Displays room number and add the method Display_Guest()
int Get_Capacity();
int Get_Status();
double Get_Rate();
int Change_Status(int);
double Change_Rate(double);
void Display_Guest();
};
 HotelRoom::~HotelRoom()
{
cout << endl<<endl;
cout << "Guest in room "<<room_num << " has checked out." <<endl;
}
 int HotelRoom::Display_Number()
{
return room_num;
}
 int HotelRoom::Get_Capacity()
{
return room_cap;
}
 int HotelRoom::Get_Status()
{
return occup_stat;
}

    int HotelRoom::Change_Status(int occup)
{
occup_stat = occup;
if (occup > room_cap)
{
    return -1;
}
else
return occup_stat;
   }
   double HotelRoom::Get_Rate()
  {
return daily_rt;
  }
   double HotelRoom::Change_Rate(double rate)
  {
daily_rt = rate;
    return daily_rt;
  }
   int Transfer(HotelRoom& room_r1, int transroom)
  {
//if guest transfers to different hotel room, room is vacant and transroom is now        occupied
room_r1.room_num = room_r1.transroom_num;

return room_num;
  }

   int main()
 {
cout<< setprecision(2)
    <<setiosflags(ios::fixed)
    <<setiosflags(ios::showpoint);
   int room = 0; 
   int roomcap = 4;
   int transroom;
   int occup;
   double rate = 89.00;

   cout<<"nEnter the room number: "<<endl;
   cin>>room;
   cout<<"nEnter the amount of guest to occupy this room: "<<endl;
   cin>>occup;

   cout<<"nThe guest has decided to transfer rooms"<<endl;
   cout<<"nEnter the room to transfer the guest to"<<endl;
   cin>>transroom;
   HotelRoom room1(room,roomcap, occup, transroom, rate ); //initialize the object
   if (room1.Change_Status(occup) == -1)
   {
cout<<"You have exceeded the room capacity"<<endl;
   }
   else
   {
    cout <<"nThe room number is ";
    room1.Display_Number();
    cout<<"."<<endl;
    cout<<"nThe name of the primary guest is ";
    room1.Display_Guest();
    cout <<"."<<endl;
    cout<<"nThe number of guest in the room is "<<room1.Change_Status(occup)<<"."    <<endl;
   cout<<"nThe daily rate for room "<<room<< " is "<<room1.Get_Rate()<<"."<<endl<<endl;

   cout<<"nYou have tranferred the guest from room"<<room1.Display_Number()<<"to"     <<Transfer(room1,transroom)<<endl;
    }
     cout<<"nRoom ";
     room1.Display_Number();
     cout<<" is vacant."<<endl;
     system("PAUSE");

return 0;
    }

函数 Transfer 不是一种HotelRoom的方法，您仍然试图访问其中的room_num，就好像它是一样。您需要指定您指的是哪个HotelRoom实例的哪个room_num。可能你的意思是return room_r1.room_num而不是return room_num.

同样在Transfer函数中，您从不使用参数 transroom ，而是使用 room_r1 中的transroom_num。这可能不是您想要的。

最后，您还没有实现HotelRoom的构造函数和DisplayRoom。你应该创建一个存根，只要你没有正确实现这些方法，它什么都不做或打印警告，所以你至少可以编译和链接代码。

由于您是初学者，因此我会坚持使用成员函数和类私有变量，直到您做得更好为止。

就错误消息而言，我的猜测是您正在使用的函数内部room_num无法访问 HotelRoom 类的私有部分。 请注意，我说的是猜测，这是因为您应该将文本复制并粘贴到此处的输出窗口中，以便我们可以看到到底发生了什么。

首先，您必须确定room_num是类成员变量。

int Transfer(HotelRoom& room_r1, int transroom)
{
    room_r1.room_num = room_r1.transroom_num;

    //because room_num is not non class member variable, you have to write like below.
    return room_r1.room_num;
    //return room_num;
}

其次，你没有写定义HotelRoom::HotelRoom(int,int,int,int,double)，HotelRoom::Display_Guest(void)。因此，您必须编写此构造函数和函数以避免错误LNK2019。

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