程序代码：

#include<stdio.h>
#include<string.h>
/*数据结构设计*/
typedef int keytype;
typedef struct Student
{

 keytype sno;

 float ChineS;

 float MathS;

 float EnglS;

 float SumS;

 float AveS;

 struct Student *next;
}linkStu;

/*输入学生成绩,并插入学生信息*/
linkStu *InputStu(linkStu *L)
{

 linkStu *p,*stu;

 int s;

 float cs,ms,es;

 p=(linkStu *)malloc(sizeof(linkStu));

 p=L;

 stu=(linkStu *)malloc(sizeof(linkStu));

 stu->next=NULL;

 printf("请输入学生的sno cs ms es:\n");

 scanf("%d,%f,%f,%f",&s,&cs,&ms,&es);

 stu->sno=s; stu->ChineS=cs;stu->MathS=ms;stu->EnglS=es;

 stu->SumS=stu->ChineS+stu->MathS+stu->EnglS;

 stu->AveS=(stu->ChineS+stu->MathS+stu->EnglS)/3;

 if(p->next==NULL)
   p=stu;

 else

 {while(p->next!=NULL&&p->sno<stu->sno) p=p->next;
  p->next=stu;

 }

 free(stu);

 return L;
}

/*输出所有学生的成绩*/
void OutputStuA(linkStu *L)
{

 linkStu *p;

 p=L;

 printf("sno\tChineseScore\tMathScore\tEnglishScore\tSumScore\tAverageScore\n");

 printf("%d\t%f\t%f\t%f\t%f\t%f\t\n",p->sno,p->ChineS,p->MathS,p->EnglS,p->SumS,p->AveS);

 p=p->next;

 if(p->next!=NULL)
  printf("%d\t%f\t%f\t%f\t%f\t%f\t\n",p->sno,p->ChineS,p->MathS,p->EnglS,p->SumS,p->AveS);
}


/*显示按照指定分数段以及科目*/
void OutputStu(linkStu *L,float l,float h,char object)
{

 linkStu *p;

 p=L;

 if(object='c')

 {
  if(p->next!=NULL)
  {
   if(p->ChineS>=l||p->ChineS<=h)
   printf("%d\t%f\t%f\t%f\t%f\t%f\t\n",p->sno,p->ChineS,p->MathS,p->EnglS,p->SumS,p->AveS);
  }

 }
if(object='m')
{
  if(p->next!=NULL)
  {
   if(p->MathS>=l||p->MathS<=h)
   printf("%d\t%f\t%f\t%f\t%f\t%f\t\n",p->sno,p->ChineS,p->MathS,p->EnglS,p->SumS,p->AveS);
  }

 }
if(object='e')
{
  if(p->next!=NULL)
  {
   if(p->EnglS>=l||p->EnglS<=h)
   printf("%d\t%f\t%f\t%f\t%f\t%f\t\n",p->sno,p->ChineS,p->MathS,p->EnglS,p->SumS,p->AveS);
  }

 }
}



/*统计班级人数*/
int CountStu(linkStu *L)
{

 int count;

 linkStu *p;

 p=L;

 count=0;

 if(p->next!=NULL) count++;

 return count;
}

/*班级的平均成绩*/
float AveScore(linkStu *L)
{

 linkStu *p;

 int j;

 float sum,ave;

 p=L;

 sum=0;

 j=CountStu(L);

 if(p->next!=NULL)
  sum=sum+p->AveS;

 ave=sum/j;

 return ave;
}

/*删除指定学生信息*/
linkStu *DeleteStu(linkStu *L,char sno)
{

 linkStu *p,*q;

 p=L;

 q=L->next;

 while(q!=NULL&&q->sno!=sno)

 {
  p=q;
  q=q->next;

 }

 if(q==NULL) printf("您所要删除的学生不存在\n");

 else

 {
  q->next=q->next;
  free(q);

 }
return L;
}

void main()
{

 int i;linkStu *L;int sno;

 L=(linkStu *)malloc(sizeof(linkStu));

 L->next=NULL;

 printf("******************************选择您所需要的操作*************************\n\n");

 printf("**************************************菜单*******************************\n\n");

 printf("********************************1、插入学生******************************\n\n");

 printf("******************************2、查看学生信息****************************\n\n");

 printf("********************************3、班级人数******************************\n\n");

 printf("**********************************0、退出********************************\n\n");

 scanf("%d",&i);

 while(i!=0)

 {
  if(i=1) InputStu(L);
  if(i=2) OutputStuA(L);
  if(i=3) CountStu(L);
}

}