How to fix: Exception thrown: read access violation. **_Pnext** was 0xFDFDFE05

Question

I'm trying to "build" a house which contains rooms. My teacher told me to do it with composition. My idea was to generate as many Rooms objects as many rooms my house has. I tried it with the following code but in the house.cpp's constructor my for cycle runs only once than it crashes at the line rooms[i] = load; with Exception thrown: read access violation. _Pnext was 0xFDFDFE05.

Here's my code:

main.cpp: '''

#include <iostream>  
#include "House.h"  
#include "Rooms.h"

using namespace std;

int main()  
{  
    Rooms basic("basic");  
    House house(basic,2);  
    house.setRooms();  
    house.setWhichroom(1);  
    cout << house.getRooms().getRoomname();  

    return 0;  
}

''' house.h: '''

#pragma once  
#include <iostream>  
#include <string>  
#include "Rooms.h"  

using namespace std;  

class House  
{  
    Rooms* rooms;  
    unsigned roomcount;  
    unsigned whichroom = 0;  
 
public:  

    House();  
    House(const Rooms&, unsigned);  
    House(unsigned);  
    ~House();  
    void setRoomcount(unsigned);  
    unsigned getRoomcount()const;  
    void setWhichroom(unsigned );  
    unsigned getWhichroom()const;  
    void setRooms();  
    Rooms getRooms()const;  

};

''' house.cpp: '''

#include "House.h"  

House::House(const Rooms& load, unsigned rc)  
{  
    roomcount = rc;  
    for (int i = 0; i < roomcount; i++)  
    {  
        rooms = new Rooms;  
        rooms[i] = load;  
    }  
}  

House::House(unsigned x):roomcount(x)  
{  
}  

House::~House()  
{  
    roomcount = 0;  
    delete rooms;  
}  

void House::setRoomcount(unsigned x)  
{  
    roomcount = x;  
}  

unsigned House::getRoomcount() const  
{  
    return roomcount;  
}  

void House::setWhichroom(unsigned x)  
{  
    whichroom = x;  
}  
  
unsigned House::getWhichroom() const  
{  
    return whichroom;  
}  

void House::setRooms()  
{  
    for (unsigned i = 1; i <= roomcount; i++)  
    {  
        char c = i;  
        string s = "room";  
        s += c;  

        rooms[i].setRoomname(s);  
    }  
}  

Rooms House::getRooms() const  
{  
    return rooms[whichroom];  
}  

''' rooms.h: '''

#pragma once  
#include <iostream>  
#include "Things.h"  

using namespace std;  

class Rooms  
{  
protected:  

    string roomname;  
    Things things;  

public:  

    Rooms();  
    Rooms(string);  
    ~Rooms();  
    void setRoomname(string);  
    string getRoomname()const;  
    void setThings();  
    unsigned getThings()const;  
};  

''' rooms.cpp:

'''

#include "Rooms.h"  

Rooms::Rooms()  
{  
}  

Rooms::Rooms(string name)  
{  
    roomname = name;  
}  

Rooms::~Rooms()  
{  
}  

void Rooms::setRoomname(string name)  
{  
    roomname = name;  
}  

string Rooms::getRoomname() const  
{  
    return roomname;  
}  
 
void Rooms::setThings()  
{  
    things.setOnoff();  
}  

unsigned Rooms::getThings() const  
{  
    return things.getOnoff();  
}  

'''

Answer 1

The problem is in the House constructor, where you have

for (int i = 0; i < roomcount; i++)  
{  
    rooms = new Rooms;
    rooms[i] = load;  
}

You will create one single Rooms object, but treat it as an array of multiple rooms.

You also create and create and create new Room objects each iteration of the loop, making you loose the earlier objects.

The simple solution, if you need to continue to use explicit memory handling yourself, is to allocate the objects once and before the loop:

rooms = new Rooms[roomcount];
for (int i = 0; i < roomcount; i++)  
{  
    rooms[i] = load;  
}

Since you now use new[] you must match it with a delete[] in the destructor. And you need to learn about the rules of three and five.

---

To simplify your code I implore you to use a std::vector instead, as that will make life so much simpler for you as a C++ programmer.