数据结构学习（C++）——单链表（定义与实现）[9]

       void first()//移动current到表头

       {

              current = first;

              prior = null;

       }

       void end()//移动current到表尾

       {

              if (last->link != null)

              {

                     for ( ;current->link != null; current = current->link)

                     prior = current;

                     last = current;

              }

              current = last;       

       }