Phong.h
class Phong
{
protected:
   bool status;
public:
   Phong();
   void xuat();
   void datPhong();
   void traPhong();
   float giaPhong();
   int dungLuong();
   bool KT_Trong();
   bool KT_Vip();
};

PhongThuong.h
#include "Phong.h"
class PhongThuong : public Phong
{
private:
   int coPhong;
public:
   PhongThuong(int coPhong);
   void xuat();
   float giaPhong();
   int dungLuong();
   //bool KT_Trong();
   bool KT_Vip();
};


PhongVip.h
#include "Phong.h"
class PhongVip : public Phong
{
private:
   int hangPhong;
public:
   PhongVip(int hangPhong);
   void xuat();
   float giaPhong();
   float khuyenMai();
   int dungLuong();
   //bool KT_Trong();
   bool KT_Vip();
};


Phong.cpp

#include <iostream>
using namespace std;

#include "Phong.h"

Phong :: Phong()
{
   this -> status = true;
}

void Phong ::datPhong()
{
   this -> status = false;
}

void Phong :: traPhong()
{
   this ->status = true;
}

bool Phong ::KT_Trong()
{
   return this -> status;
}

void Phong :: xuat()
{
   cout << "Tinh trang: ";
   if(this -> status ==true)
   {
      cout << "Trong" << endl;
   }
   else
      cout << "Co khach" << endl;
}

float Phong :: giaPhong()
{
   return -1;
}

int Phong ::dungLuong()
{
   return 0;
}

bool Phong ::KT_Vip()
{
   return false;
}


PhongThuong.cpp

#include <iostream>
using namespace std;

#include "PhongThuong.h"

PhongThuong :: PhongThuong(int coPhong)
:Phong()
{
   this -> coPhong = coPhong;
}


void PhongThuong :: xuat()
{
   this ->Phong::xuat();
   cout << "Co phong" << this ->coPhong << endl;
}

float PhongThuong :: giaPhong()
{
   return 5+5*this->coPhong;
}

int PhongThuong ::dungLuong()
{
   return this->coPhong;
}

bool PhongThuong ::KT_Vip()
{
   return false;
}


PhongVip.cpp

#include <iostream>
using namespace std;

#include "PhongVip.h"

PhongVip :: PhongVip(int hangPhong)
:Phong()
{
   this -> hangPhong = hangPhong;
}


void PhongVip :: xuat()
{
   this ->Phong::xuat();
   cout << "Hang phong" << this ->hangPhong << endl;
}

float PhongVip :: giaPhong()
{
   switch (this ->hangPhong)
   {
   case 1: return 100;
   case 2: return 80;
   case 3: return 50;
   default: return -1;
   }
}

int PhongVip ::dungLuong()
{
   return this->hangPhong;
}

bool PhongVip ::KT_Vip()
{
   return false;
}

main.cpp

void main()
{}