add to the beginning of a circular (singly) linked list

Hi there. Long time no read :)

I have a problem with my circular list. I can add a node to the end of the list just fine, but I can't seem to add it to the beginning.

This is (sort of a pseudocode) for my adding to the end of the list

Code:

---

if (*head == NULL)
{
        *head = new;
        (*head)->next = *head;
}
else
{
        last  = *head;
        while (last->next != *head)
                last = last->next;
               
        new->next = *head;
        last->next = new;
}

---

I tried this for adding to beginning of the list but after adding the seccond node the program just stalls.

Code:

---

if (*head == NULL)
{
        *head = new;
        (*head)->next = *head;
}
else
{               
        new->next = *head;
        *head = new;
}

---

Well.....I don't know how your determining beginning and end in a circular list?
Hence
Considering one node circular list, next pointer of first node will be pointing to itself and hence definitely not null....

I think I didn't make my self clear. When I said "end" i thought "after the last node in the list" or more precisely "before the beginning in the list"

Quote:

---

Originally Posted by budala

Code:

---

if (*head == NULL)
{
        *head = new;
        (*head)->next = *head;
}
else
{               
        new->next = *head;
        *head = new;
}

---

---

wait this is not circular.....here u need to configure the previous node's next to point the new head. Considering two nodes in a circle the next pointer of second has to point the head. Which is not happening in the lines....

got it!