Question

Trying to figure out why my list() class pointers are being overwritten with the third node. What happens in the insert function (below) is that the third time the insert function is called my headByName->nextByName node pointer is overwritten by the third node, when it should point to the second. So as you can guess the 4th node is overwritten by the 5th and the 6th node is overwritten by the 7th, hence the “jump” in nodes.

The attributes of the winery object are passed through the winery ctor and then to the list::insert function via these calls in main:

//main.cpp
//the attributes of the winery object are the paramaters, name, location, acres, rating:
list *listPtr = new list();
wineries->insert(winery("Lopez Island Vinyard", "San Juan Islands", 7, 95));
wineries->insert(winery("Gallo", "Napa Valley", 200, 25));
wineries->insert(winery("Cooper Mountain", "Willamette Valley", 100, 47));

Then the winery ctor is called where I allocate the private pointer memembers:

//winery.cpp
winery::winery(const char * const name, const char * const location, const int acres, const int rating)
  : m_acres( acres ), m_rating( rating )
{
    if (name)
    {
        size_t len = strlen( name ) +1;
        m_name = new char[len];
        strcpy_s( m_name, len, name );
    }
    else
        m_name = NULL;

    if (location)
    {
        size_t len = strlen( location ) +1;
        m_location = new char[len];
        strcpy_s( m_location, len, location );
    }
    else
        m_location = NULL;
}

And then to the issue at hand: If you can imagine this function has already been called twice then current_node will have the thrid winery. headByName will have the first node and in it [+], headByName->next will have the third. I need headByName->next to have the second. I am just wondering why it has been overwritten..

// list.cpp
void list::insert(const winery& winery)
{
    node *current_node  = new node( winery ); // the third wineries info!
    node *next_node     = NULL;
    list *list_ptr      = NULL;
    do
    {
        if ( headByName == NULL || headByRating == NULL ) // then we are here for the first item
        {   
            headByName   = current_node; // the list ptrs have a node address. 
            headByRating = current_node;
        } 
        else
        {           

            next_node                  = current_node; 
// transfer by the next call in main.
            headByName->nextByName     = next_node;
            headByRating->nextByRating = next_node;

        }
    } while ( headByName == NULL || headByRating == NULL );

    next_node    = NULL;
    current_node = NULL;
}

Could someone please find my second node?
oh yeah, and the pointers that are available to me:

struct node
{
    winery  item;
    node *  nextByName;
    node *  nextByRating;
};

class list
{
    ...
private:
    node * headByName;
    node * headByRating;
};

this might be of some importance, its the body of the node ctor:

//list.cpp
list::node::node(const winery &winery) :
nextByName( NULL ), nextByRating( NULL ), item( winery.getName(),
winery.getLocation(), winery.getAcres(), winery.getRating() )
{
    // where the item paramters are all pub-mem functions of the winery class.  

}

Answer 1

I think that problem is here:

headByName->nextByName     = next_node;
headByRating->nextByRating = next_node;

You’re always override second node. As I understand you should find last one by iterating through whole list and insert after last node.