Given a single linked list write a function to swap each pair of nodes by manipulating with pointers (not values).?

Sol:
Original list: head->1->2->3->4->5->NIL should be transformed to head->2->1->4->3->5-> NIL

int reverse_pairs(LLIST ** head)
{
LLIST * temp = ULL;
LLIST* current_pair = *head;
LLIST** previouspair = head;
while((current_pair != NULL) && (current_pair->next != NULL))
{
temp = current_pair;
current_pair = current_pair->next;
temp->next = current_pair->next;
current_pair->next = temp;
*previouspair = current_pair;
current_pair = temp->next;
previouspair = &temp->next;
}
return 0;
}