C++ Finde den Fehler: Doppelt verkettete Liste

//
//  main.cpp
//  Aufgabe5
//
//  Created by du on 06.12.11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#include <iostream>

using namespace std;

struct ListElem{
private:
    ListElem* m_Next;
    ListElem* m_Prev;
    int m_Elem;
    
public:
    int getElem(){
        return m_Elem;
    }
    
    void setPrev(ListElem* elem){
        m_Prev = elem;
    }
    
    ListElem* getPrev(){
        return m_Prev;
    }
    
    void setNext(ListElem* next){
        m_Next = next;
    }
    
    ListElem* getNext(){
        return m_Next;
    }
    
    void setElem(int elem){
        m_Elem = elem;
    }
    
    ListElem(int elem, ListElem* next, ListElem* prev){
        m_Next = next;
        m_Prev = prev;
        m_Elem = elem;
        
        if(m_Next != 0)
            m_Next->setPrev(this);
        if (m_Prev != 0)
            m_Prev->setNext(this);
    }
};

struct DoubleList{
    ListElem* m_Head;
    ListElem* m_Tail;
    
    DoubleList(){
        m_Head = 0;
        m_Tail = 0;
    }
    
    void pushFront(int elem){
        if(m_Head == 0)
            m_Head = m_Tail = new ListElem(elem, 0, 0);
        else
            m_Head = new ListElem(elem, m_Head, 0);
    }
    
    void pushBack(int elem){
        if(m_Tail == 0)
            m_Tail = m_Head = new ListElem(elem, 0, 0);
        else
            m_Tail = new ListElem(elem, 0, m_Tail);
    }
    
    void addElement(int elem){
        m_Tail = m_Head;
        m_Head = new ListElem(elem, m_Head, 0);
    }
    
    void print(){
        for (ListElem* elem = m_Head; elem != 0; elem->getNext()) {
            cout << elem->getElem() << endl;
        }
    }
};

int main (int argc, const char * argv[])
{
    DoubleList dl;
    dl.addElement(5);
    dl.addElement(10);
    /*
    dl.pushFront(5);
    dl.pushBack(10);
    dl.pushFront(10);
    dl.pushFront(15);
    dl.pushFront(25);
    dl.pushFront(35);
     */
    dl.print();
    return 0;
}

void print(){
        for (ListElem* elem = m_Head; elem != 0; elem = elem->getNext()) {
            cout << elem->getElem() << endl;
        }
    }