Help with my doubly linked list

Code:

---

#include <iostream>

using namespace std;

struct dNode
{
        int info;
        dNode *next; //link to next node
        dNode *back; //link to previous node
};

void main(void)
{
        dNode *head, *tail, *newNode *current;
        head = tail = newNode = NULL;

        newNode = new dNode;
        newNode->info = 55;
        newNode->next = NULL;
        newNode->back = NULL;
        cout << "My first node is " << newNode -> info << endl;

        head = tail = newNode;

        newNode = new dNode;
        newNode->info = 514;
        newNode->next = NULL;
        newNode->back = NULL;
        cout << "My second node is " << newNode -> info << endl;
        tail->next = newNode;

        newNode = new dNode;
        newNode->info = 27;
        newNode->next = NULL;
        newNode->back = NULL;
        cout << "My third node is " << newNode -> info << endl;
        tail->next = newNode;

        newNode = new dNode;
        newNode->info = 35;
        newNode->next = NULL;
        newNode->back = NULL;
        cout << "My fourth node is " << newNode -> info << endl;
        tail->next = newNode;
        cout << "End of building a linked list: " << endl;    //end of building a linked list

        cout << "Transvering " << endl;                        //start to transverse
        current = head;                                        //set current pointer to the first
       

        system ("pause");
}

---

I am now doing the doubly linked list. I not sure what should I do to transverse and print the values using cout. Because, doubly linked list got 2 linking to the next nodes and I am totally stucked on what to do.

When you're adding to the end of a DL list, you do

node->next = NULL;
node->back = tail;
tail->next = node;
tail = node;

Code:

---

#include <iostream>
 
using namespace std;
 
struct nodeType
{
    int info;
    nodeType * link;
};
 
int main()
{
    nodeType * first, * last, *newNode, * current ,*previous;
    first = last = newNode = NULL;
 
   
 
   
    cout << "Building a linked list: " << endl;
 
    newNode = new nodeType;                                  //create a first node
    newNode -> info = 5;                                    //first node = 5;
    newNode -> link = NULL;                                  //make the first link to NULL first
    cout << "My first node is " <<newNode -> info << endl;  //print the first node = 5
   
 
    first = last = newNode;                                  //ensure pointer first and last is in first node
                                       
    newNode = new nodeType;                                  //create a second node                               
    newNode -> info = 15;                                    //second node = 15;
    newNode -> link = NULL;                                  //make the second link to NULL first
    cout << "My second node is " <<newNode -> info << endl;  //print the second node = 15
    last->link = newNode;                                    //link to the second node from the first node
    last = newNode;                                          //set last point to the second node
 
    newNode = new nodeType;                                  //create the third node
    newNode -> info = 10;                                    //third node = 10;
    newNode -> link = NULL;                                  //make the third link to NULL first
    cout << "My third node is " <<newNode -> info << endl;  //print the third node =1 0
    last->link = newNode;                                    //link to the third node from the second node
    last = newNode;
 
    newNode = new nodeType;                                //create a fourth node
    newNode -> info = 22;                                  //fourth node = 22;
    newNode -> link = NULL;                                //make the fourth node link to NULL first
    cout << "My fourth node is " <<newNode -> info << endl; //print the fourth node
    last->link = newNode;
    last = newNode;
   
    cout << "End of building a linked list: " << endl;    //end of building a linked list
   
    //Start of Transvering
    cout << "Transvering " << endl;                        //start to transverse
    current = first;                                        //set current pointer to the first node
   
    cout << "Transvering through the first node" << endl; 
    cout << current-> info << endl;                        //5
 
    cout << "Transvering thorugh the second node" << endl;
    current = first;                                      //set current back to first node
    current = current->link ;                              //set current pointer to the second node
    cout << current -> info << endl;                      //15
 
    cout << "Transvering through the third node" << endl;
    current = first;                                        //set current back to first node
    current = current-> link->link;                        //set current pointer to third node
    cout << current -> info << endl;                      //10
 
    cout << "Transvering through the fourth node" << endl;
    current = first;                                      //set current back to first node
    current = current-> link->link->link;                  //set current pointer to fourth node
    cout << current -> info << endl;                      //22
   
    cout << "Transvering through the last node" << endl;  //trying to transverse after the fourth node, accessing after from the fourth node
    if (current == last)
    {
        cout << endl;
        cout << "No transvering allowed in fourth node: " << endl;        //error would be given since there are only 4 nodes
       
    }
    else
    {
        cout << current -> info << endl;                    //would not print and go through this else statement since it is not possible
    }
    cout << endl;
   
    cout << "Transvering back to the first node: " << endl; //back to the first node
    cout << endl;
    current = first;                                        //set current back to the first node
    cout << current -> info << endl;                        //print , 5
 
 
    //Deleting third node
   
    previous = first->link;        // Previous points to second node
    current = previous->link;      // Current points to third node
    previous->link = current->link; // 2nd node link pointer to link to the 4th node
    delete current;                // Delete the third node pointing
 
    //Print after deleting using transverse
    current = first;                //set the current back to the first node
    cout <<"New first node is " <<  current -> info << endl;    //print the first node, 5
 
    current = first;                                            //set current back to the first node                                 
    current = current ->link;                                  //set current pointing to the second node
    cout << "new Second node is " << current -> info << endl;  //print the second node, , 15
 
    current = first;                                              //set current pointing back to the first node 
    current = current ->link->link;                                //set current pointing to the fourth node since third node has been deleted
    cout << "New Third node is " << current -> info << endl;      //print 22 instead 0f 10
    cout << "Deletion of the third node is successfully." << endl;
 
    //Insertion new node between first node and third node
    //newNode = new nodeType;                                  //create a new node
    //newNode -> info = 33;                                    //first node = 33;
    //newNode -> link = NULL;                                  //make the first link to NULL first
    //cout << "My new node is " <<newNode -> info << endl;  //print the first node = 33
    //previous = first;       
    //current = current->link;
    //previous -> link = newNode;
    //newNode = current;
    //cout << current -> info << endl;
    //cout << current -> info << endl;
    //cout << current -> info << endl;
   
   
    system ("pause");
    return 0;
}

---

I managed to build a single linked list but completely unsure how to implement in double linked list. Is the pointer that I wrote enough for transverse. Maybe i add another current pointer to transverse but do I need other point just to transverse.

It might help if you had some utility functions which say
- appendNodeToList
- prependNodeToList
- insertNodeIntoList
type functions, rather than merely copy/pasting everything and hoping you get all the link pointer edits correct.

There are plenty of prior examples on the board to look at.