Recursive Print Function for Linked List

Question

So my professor would like us to design recursive functions for a linked list from this class 'addressBookType' which is derived from 4 other classes. The program basically creates an address book with the person's name, address, date, and relationship, each of those has their own classes.

The recursive functions she wants to make are a print, append, delete, and sequential search.

But here's the problem. The main premise around a function being recursive is that it's supposed to call itself in the function definition right? I successfully made the recursive append function, but I'm having trouble with the recursive print function.

Here is what the original print function and the recursive print function are:

void addressBookType::displayList() const
{
    ListNode *nodePtr; // To move through list

    nodePtr = head; // start at the head of list

    while(nodePtr != NULL) // while nodePtr points to a node, move through list
    {
        displayListRecursive(nodePtr);
        nodePtr = nodePtr->next;
    }
}

void addressBookType::displayListRecursive(ListNode *node) const
{
    if(node != NULL)
    {
        (node->value).print();

        displayListRecursive(node->next);
    }

}

The trouble I'm having is that when I run the program, everything prints and then it starts printing at the second object until there is one object left. Here's what I mean when it prints:

1
2
3
4

2
3
4

3
4

4

I would paste what the actual output is but it is VERY lengthy, as each object displays the person's first name, last name, address, street, zipcode, city, state, date, and relationship type.

Whenever I take out the displayListRecursive(node->next) in the displayListRecursive function, everything prints fine. But then it's not really a recursive function right? Or is it? Anyone have some answers that can explain this? (I'm REALLY new to recursive)

Answer 1

I think the recursive definition is fine. It will print the node you provide and then call itself with the next one until its NULL.

So you just need to call the recursive function from the first node.

The problem is that you are calling it multiple times with all the nodes in the while loop of displayList. I think that if you just remove the while loop it should work as you expect.

Something like this:

void addressBookType::displayList() const
{
    displayListRecursive(head);
}

void addressBookType::displayListRecursive(ListNode *node) const
{
    if(node != NULL)
    {
        (node->value).print();

        displayListRecursive(node->next);
    }

}