c语言成绩统计

输入若干学生若干门课的成绩,分别用函数求:①每个学生平均分;②每门课平均分;③找出最高的分数所对应的学生和课程;④求平均分方差（见教材P203）.要求使用字符仿菜单功能,程序功能及界面
操作菜单
1.修改学生人数和科目数
2.输入成绩并统计分析
3.清楚屏幕
4.退出
是C语言哈，不是c++

typedef struct{
int course;
float mark;
PMARK next;
int reserved;
}MARK,*PMARK;

typedef struct{
char name[30];
int id;
PTEACHER teacher;
PCOURSE nextcourse;
int reserved;
}COURSE,*PCOURSE;

typedef struct{
int term;
int classrank;
int graderank;
float average;
PMARK marks;
PTERMSCORE nextterm;
int reserved;
}TERMSCORE,*PTERMSCORE;

typedef struct{
char name[30];
char id[10];
char sex;
PTERMSCORE score;
PSTUDENT nextstudent;
int reserved;
}STUDENT,*PSTUDENT;

typedef struct{
char name[30];
int numofstu;
PSTUDENT student;
PTEACHER teacher;
PTERMSCORE average;
PCLASS nextclass;
int reserved;
}CLASS,*PCLASS;

typedef struct{
char name[30];
int id;
PCLASS class;
PCOURSE course;
PTEACHER nexteacher;
int reserved;
}TEACHER,*PTEACHER;