Stuff

void list_exchange(node*& head_ptr, size_t pos1, size_t pos2)	{					node* pos1_node = list_locate(head_ptr, pos1);			node* pos2_node = list_locate(head_ptr, pos2);			node* pos1_bkp = pos1_node;			node* pos2_bkp = pos2_node;			node* pos1_link = pos1_node->link();			node* pos2_link = pos2_node->link();			pos1_node = pos2_node;			pos1_node->set_link(pos2_link);					pos2_node = pos1_bkp;			pos2_node->set_link(pos1_link);			if(head_ptr == pos2_bkp)				head_ptr = pos1_node;			if(head_ptr == pos1_bkp)				head_ptr = pos2_node;			}