学生选课系统
假定有n门课程，每门课程有课程编号，课程名称，课程性质，学时，授课学时，实验或上机学时，学分，开课学期等信息，学生可按要求（如总学分不得少于15）自由选课。试设计一个选修课程系统，使之能提供以下功能：
功能要求：
(1) 系统以菜单方式工作；
(2) 课程信息和学生选课信息录入功能（课程信息用文件保存）；
(3) 课程信息浏览功能；
(4) 查询功能；
(5) 按学分查询；
(6) 某门课程学生选修情况（可选项）。(Student elective system
Assuming that there are n courses, each course has curriculum number, course name, course nature, teaching hours, teaching hours, experiment or boarding hours, credits, semester and other information. Students can freely choose courses according to requirements (such as total credits not less than 15). Try to design an elective course system to provide the following functions:
Functional requirements:
(1) the system works by menu;
(2) the information of the course and the information entry function of the students' elective courses (the document is saved for the course information).
(3) the function of course information browsing;
(4) query function;
(5) to inquire according to the credit score;
(6) the elective situation of a student in a course (optional))