NODE *create_node(const char *name, const char *num, NODE *prev, NODE *next)
{
        int n;

        NODE *mem=malloc(sizeof(NODE));
        if(mem == NULL) return(NULL);

        strncpy(mem->number, num, sizeof(mem->number));
        mem->number[sizeof(mem->number)-1]='\0';

        strncpy(mem->name, name, sizeof(mem->name));
        mem->name[sizeof(mem->name)-1]='\0';
        for(n=0; mem->name[n] != '\0'; n++)
                mem->name[n]=topper(mem->name[n]);

        mem->next=next;
        mem->prev=prev;
        return(mem);
}

void insert(NODE *node)
{
        node *h=head;

        if(h == NULL) // List is empty, just set it to this node
        {
                head=node;
                return;
        }

        // Loop until the end of the list,
        // but STOP at the last one.  h will not be NULL after this loop.
        while(h -> next != NULL)
        {
                int v=strcmp(node->name, h->name);

                if(v == 0) return; // Reject duplicate
                else if(v < 0)
                {
                        h=h->next;
                        continue;
                }

                // We want to change a <-> b <-> d <-> e into
                // a <-> b <-> c <-> d <-> e
                // We are at node d.

                // point ahead to d
                node->next=h;
                // point back to b
                node->prev=h->prev;

                // make b point ahead to us
                if(h->prev != NULL) h->prev->next=node;
                // make d point back to us
                h->prev=node;

                return;
        }

        if(h->next == NULL) // append to list
        {
                h->next=node;
                node->prev=h;
                return;
        }
}