Initializing a pointer in a class.

Im having a little trouble with a program i am writing. I have a class heirarchy:

Project
--> SimpleProject
--> MinorProject
ect...

and another class:
Task

Now task has a pointer to a Project object in it's private section of the class definition.

Here is Task.h

Code:

---

#ifndef TASK_H
#define TASK_H

// forward declaration
class Project;

class Task
{

public:
        Task();       
        Task(const Task & t);
        Task(int, const Project &);       
        ~Task();

        void DoIt();

        Task & operator=(const Task & other);
        friend std::ostream & operator<<(std::ostream & os,
                                                                        const Task & t);
        friend bool operator==(const Task & left,
                                                  const Task & right);
        friend bool operator!=(const Task & left,
                                                  const Task & right);

private:
        int id;
        Project *pp;

};

#endif

---

Now i want the Project *pp pointer to point to a derived class of Project (SimpleProject, MinorProject).

I defined the constructors of Task like this (Task.cpp):

Code:

---

/**
* Default Constructor
*/
Task::Task()
{
        // do nothing
}

/**
* Constructor with id and reference to project.
*/
Task::Task(int in_id, const Project & in_pp)
{
        *pp = in_pp; // is this wrong?
        id = in_id;
}

/**
* Copy Constructor.
*/
Task::Task(const Task & orig)
{
        id = orig.id;       
        pp = orig.pp;

}

---

Of so the id is getting set but for some reason the pp pointer is not being set. It is always the same memory address for each pp pointer even if i create more than on instance of the class. Do i have to dynamically create the Project that pp is pointing to in the constructors? But if i do that then i will have to know what type of project it is.

My main file is:

Code:

---

#include <iostream>
#include <iomanip>

using namespace std;

#include "Task.h"
#include "SimpleProject.h"
#include "MinorProject.h"
#include "MajorProject.h"

int main()
{
        SimpleProject *sp1 = new SimpleProject();
        SimpleProject *sp2 = new SimpleProject(*sp1);
        SimpleProject *sp3 = new SimpleProject(*sp1);
       
        Task *t1 = new Task(1, *sp1);
        Task *t2 = new Task(2, *sp2);
        Task *t3 = new Task(*t1);

        sp1->AddTask(*t1);
        sp2->AddTask(*t2);
        sp3->AddTask(*t3);

        cout << *sp1 << endl;
        cout << *sp2 << endl;
        cout << *sp3 << endl;

        cout << (*sp1 == *sp2) << endl;

        delete sp1;
        delete sp2;
        delete sp3;

        return 0;
}

---

The only thing that is not working is the pp pointer in Task obejcts.
Can anyone help me out?

>> *pp = in_pp; // is this wrong?

Yes. That copies the data in in_pp to whatever pp points to. What you want to do is assign the address of in_pp to pp. Of course, if pp is a pointer, you might as well make in_pp a pointer.

You should initialize pp to 0 in the default constructor, or just makie pp a reference variable itself and get rid of the default constructor. You should also make more descriptive variable names than pp.

Quote:

---

Code:

---

Task::Task(int in_id, const Project & in_pp)
{
        *pp = in_pp; // is this wrong?
        id = in_id;
}

---

---

yes it is wrong
*pp dereferences the pointer, but there is no object it's pointing at so nothing to dereference.
You should just use: pp = &in_pp;
to assign the pointer to the passed in object

Thanks alot. I understand what i was doing wrong now.

And yes, i was being lazy with my naming conventions. It's an awful habbit...