C++ Double Linked List Reverse Print - c++

Question

I am trying to write a reverse print function as part of a doubly linked list. Here are the relevant functions that I have written:
void PLAYER::AddNode(int addID, std::string addName){
nodePtr n = new node; //creates a new node pointer
n->next = NULL; //Make next null
n->prev = NULL; // this will set this to be the ending node
n->ID = addID; //These two lines pass the information into the node
n->name = addName; // ID# and Name Information
if(head != NULL){ // This checks to see if a list is set up.
curr = head; // Make this point to the head.
while(curr->next != NULL){ // Loops through until the NULL is found
curr = curr->next;
}
curr->next = n; //Make the currnet node point to N
n->prev = curr; //Make the previous node connect to curr
n->next = tail; // connect new node to the tail.
}
else{
head = n; //If there is no list, this makes N the first node.
}
Here is the class that prototypes the functions to be used.
class PLAYER
{
public: // Functions go inside PUBLIC
PLAYER();
void AddNode(int addID, std::string addName);
void DeleteNode(int delPlayer);
void SortNode();
void PrintList();
void InsertHead(int AddID, std::string addName);
void PrintReverse();
private: //Variables go into here
typedef struct node{
// ...
std::string name;
int ID;
node* next;
node* prev;
}* nodePtr;
nodePtr head, curr, temp, prev, test, tail;
};
And finally my attempt to create a reverse traversing function to print backwards.
void PLAYER::PrintReverse()
{
curr = head;
while(curr->next != NULL) //Get to the end of the list
{
curr = curr->next;
}
while(curr->prev != NULL) //Work backward and print out the contents
{
std::cout << curr->ID << " " << curr->name << endl;
curr = curr->prev;
}
}
What I would like to do is inside the PrintReverse() function have it initialize via the tail pointer, however I can not figure out the functions to add to PrintReverse() and to AddNode() in order to have the new nodes pointed to by tail.
This is my first question posting here, I hope I covered all my bases. Thank you for any help I can find.
EDIT:
Thank you for all your input. I am relearning data structures and yes this is some self imposed homework on my part to begin to get the logic flowing again.
I will make the changes when I get home tonight.

Answer 1

The following changes would need to be considered.
The PrintReverse function would not need the forward pass to obtain the tail.
void PLAYER::PrintReverse()
{
curr = tail;
while(curr != NULL) //Work backward and print out the contents
{
std::cout << curr->ID << " " << curr->name << endl;
curr = curr->prev;
}
}
There is a problem in how tail is handled in the AddNode function. See the lines where the comments contain [CHANGED] and [ADDED]:
if(head != NULL){ // This checks to see if a list is set up.
curr = head; // Make this point to the head.
while(curr->next != NULL){ // Loops through until the NULL is found
curr = curr->next;
}
curr->next = n; //Make the currnet node point to N
n->prev = curr; //Make the previous node connect to curr
n->next = NULL; // [CHANGED]: we want the last node not to have a successor.
}
else{
head = n; //If there is no list, this makes N the first node.
}
tail = n; // [ADDED]: the last node added is the new tail.
However, a simpler solution is to avoid again the forward pass, and start from tail.
if(tail != NULL){ // This checks to see if a list is set up.
tail->next = n; //Make the old tail node point to N
n->prev = tail;
n->next = NULL;
}
else{
head = n; //If there is no list, this makes N the first node.
}
tail = n; // The last node added is the new tail.