有五个学生,每个学生有3门课的成绩,从键盘输入以上数据(包括学生号,姓名,三门课成绩),计算出 平均成绩,况原有的数据和计算出的平均分数存放在磁盘文件"stud"中.-There are five students, each student will have a 3 course results from more than keyboard input data (including student number, name, course grades), calculated