Question

I’m trying to implement my own list class but am having trouble reversing just part of my list.

Revelant code:

void List<T>::reverse(ListNode * & head, ListNode * & tail)
{

    ListNode* t;
    ListNode* curr = head;
    ListNode * funtail = tail;
    int stop=0;
    while(stop==0)
    {
        if(curr==funtail)
        {
            stop = 1;
        }
        t = curr->prev;
        curr->prev = curr->next;
        curr->next = t;
        curr = curr->prev;
    }
    t = tail;
    tail = head;
    head = t;
}

If I start with the list

1 2 3 4 5 6 7 8 9 10

and I pass in pointers to 1 and 4, then the list should look like

4 3 2 1 5 6 7 8 9 10

The problem is, my list returns as just

1

with the rest of the list lost (well, still accessible from my global tail variable). Any ideas? Is my method wrong?

Answer 1

Your head->prev must be pointing to NULL in first for loop . You better think and implement digramatically it will be helpful . You need t->next->next =t->next.