学生成绩管理的数据结构；要求完成：学生数据的录入、添加、修改与删除；成绩统计并排名；显示；学生数据的读取与存储等基本功能(只需录入3门左右成绩即可)-Student performance management data structure　required to complete: Student data entry, add, modify and delete　score statistics, and ranking　display　students to read and store data and other basic functions (Zuo You only need to input three results can be)