student

代码说明：

  定义两个类，techer类和student类，将student类对象转换为techer类对象，假设学生毕业后留校，其相关 数据仍然有用，如编号num，姓名name，性别sex。转换后输出相关数据(Define two classes, techer class and student class, the student class object is converted to techer class object, assuming that the students stayed after graduation, the related data is still useful, such as the number num, name name, sex sex. The converted output data)

文件列表：

student.txt,1470,2010-06-10