双向链表能够双向循环，具备查找、添加、删除等多种功能。-Capable of two-way circular doubly linked list, with search, add, delete, and other features.

利用链式存储结构存储学生的成绩信息，定义学生结构体类型，建立双向循环链表-The chain store structure is used to store the students performance information, and to define the structure of the students, and to establish a two-way circular linked list.