说明：  完整的成绩管理系统，功能如下，添加学生信息，查看学生信息，按学号查找学生信息，按姓名查找学生信息，按平均成绩排序，删除学生信息，保存学生信息，打开文件，我的信息，退出。
(The complete achievement management system has the following functions: adding student information, viewing student information, searching student information by student number, searching student information by name, sorting by average score, deleting student information, saving student information, opening file, and withdrawing.)