iterator help

[thescratchy]

Hello, I am trying to create a container/iterator.
But I am stuck.

My Add Function is wrong, I'm not using pointers correctly.
But here is the thing:

I need to make this ex without the functions : Next(), Head(), Tail() returning a pointer.

Please can someone help me?

#include <iostream>
using namespace std;


typedef enum{YELLOW, RED, GREEN, BLUE} LegoPieceColor;

class LegoPiece{

private:
    LegoPieceColor m_color;
    int m_height, m_width, m_length;
public:
    LegoPiece(LegoPieceColor color, int height, int width, int length)
        : m_color(color),m_height(height),m_width(width),m_length(length){}

    virtual ~LegoPiece(){}

    friend std::ostream& operator<<(std::ostream& ostr, const LegoPiece& piece){
        ostr << piece.m_color << piece.m_height << piece.m_width << piece.m_length;
        return ostr;
    }

    LegoPiece(const LegoPiece &other)
    {
        cout << "sup\n";
        m_height = other.m_height;
        m_length = other.m_length;
        m_width = other.m_width;
        m_color = other.m_color;
    }
};

class Box{
public:

    //Iterator
    class Iterator{
        friend class Box;
        LegoPiece *m_pPiece;
        Iterator *m_pNext;

    public:
        Iterator(LegoPiece* piece = 0, Iterator *next = 0){
            m_pPiece = piece;
            m_pNext = next;
        }

        Iterator(const Iterator &it){
            this->m_pPiece = it.m_pPiece;
            this->m_pNext =  it.m_pNext;
        }

        virtual ~Iterator(){
            //delete m_pPiece;
            //delete m_pNext;
        }

        Iterator Next()const{
            return *m_pNext;
        }

        LegoPiece* GetLegePiece()const{
            return m_pPiece;
        }

        bool operator==(const Iterator &it){
            if (it.m_pPiece == this->m_pPiece)
                return true;
            else
                return false;
        }

        bool operator!=(const Iterator &it){
            if (it.m_pPiece == this->m_pPiece)
                return false;
            else
                return true;
        }


    };

private:
    Iterator *m_pHead, *m_pTail;
    char *m_name;

public:
    Box(const char* name = 0){
        m_name = new char[strlen(name) + 1];
        strcpy(m_name, name);

        m_pHead = NULL;
        m_pTail = new Iterator();
    }

    virtual ~Box(){
        // Delete everything
    }

    Iterator Head()const{
        return *m_pHead;
    }
    Iterator Tail()const{
        return *m_pTail;
    }

   /* friend std::ostream& operator<<(std::ostream& ostr, const Box& b){
        Iterator it;
        for(it =b.Head(); it.Next() != b.Tail(); it = it.Next())
        {
            cout << "sdf\n";
            ostr <<*it.GetLegePiece() << endl;
        }
        return ostr;
    }
*/
    void Add(LegoPiece *piece){

        if(m_pHead == NULL){
            m_pHead = new Iterator(piece, m_pTail);


        } else {
            Iterator it;
            for(it = Head(); it.Next() != Tail(); it = it.Next());

            it.m_pNext = new Iterator(piece, m_pTail);




        }
    }
};

int main(void){

    LegoPiece *piece1 = new LegoPiece(RED, 2,1,1);
    LegoPiece *piece2 = new LegoPiece(BLUE, 2,2,1);
    LegoPiece *piece3 = new LegoPiece(YELLOW, 1,3,2);

    std::cout << *piece3 << std::endl;

    Box box("CheapBox1");
    box.Add(piece1);
    box.Add(piece2);
    box.Add(piece3);

    //cout << box << endl;



    return 0;
}

[Daved]

Is this a different problem than in your other thread? What problem are you having exactly?

[thescratchy]

Hello,
Yes, In my other thread I use functions GetNext(), Tail(), Head() that return a pointer.
In this function I am basically trying the same thing except in stead of returning pointers returning the objects.

So in my addfunction, my changes disappear after the call. Is it only possible using pointers, or is also possible letting the functions: Next(), Tail(), Head() returning the object?

Thank you

[Daved]

You should use references if you're not using pointers. The second time you add, Head() returns a copy of the head iterator, and the new item is added to the copy. Head() and Next() should return either a pointer or a reference if you're going to make it work this way, so that setting the m_pNext member works on the actual object and not the copy.