Thread: Changing single to double linked list

Double linked lists are FAR simpler than single linked lists. Trust me on this one. They make it way easier to delete nodes from. Given a single node, you can delete that node. You don't have to traverse the entire list to do it. Simply cut it free.

That being said...

Code:

struct node* newnode( ...args... )
{
    struct node *newnode;
    newnode = malloc( sizeof( struct node ) );
    newnode->prev = NULL; /*1*/
    newnode->next = someNode; /*2*/
    someNode->next = newnode; /*3*/
    someNode->prev = newnode; /*3*/
    newnode->something = somearg;
    return newnode;
}

1 - Point this to NULL if you are prepending to a list. Point this to 'someNode' if you are appending.

2 - Point this to NULL if you are appending to a list. Point this to 'someNode' if you are prepending.

3 - Use one or the other, depending if you are prepending or appending.

If you are inserting, it is slightly different, except instead of using nulls, you use 'someNode->prev', 'someNode->next', 'someNode->prev->next' and 'someNode->next->prev', depending on if you are inserting after or before 'someNode'.

Quzah.