第1步骤
#include<stdio.h>
int main(){
	char ch;
	int i; 
	for(i=1;i<=30;i++)
	printf(" ");
	printf("1.Input\n");
	 for(i=1;i<=30;i++)
	printf(" ");
	printf("2.Output\n");
	for(i=1;i<=30;i++)
	printf(" ");
	printf("3.Order\n");
	for(i=1;i<=30;i++)
	printf(" ");
	printf("4.Quit\n");
	scanf("%c",&ch);
	if(ch=='i'){
		printf("You are trying to Input info\n");
	}
	else if(ch=='o'){
		printf("You are trying to Onput info\n");
	}
	else if(ch=='m'){
		printf("You are trying to Make things ordered\n");
	}
	else if(ch=='q'){
		printf("You are about to Quit\n");
	}
	else{
		printf("Wrong input");
	}
}
第2步骤
#include<stdio.h>
int main()
{
	struct student
	{
		int num;
		float gaoshu;
		float dawu;
		float english;
		float sum;
	}student1, student2, student3;
	printf("输入学生成绩：\n");
    scanf("%d\n%f\n%f\n%f\n", &student1.num, &student1.gaoshu, &student1.dawu, &student1.english);
	scanf("%d\n%f\n%f\n%f\n", &student2.num, &student2.gaoshu, &student2.dawu, &student2.english);
	scanf("%d\n%f\n%f\n%f\n", &student3.num, &student3.gaoshu, &student3.dawu, &student3.english);
	student1.sum = student1.gaoshu + student1.dawu + student1.english;
	student2.sum = student2.gaoshu + student2.dawu + student2.english;
	student3.sum = student3.gaoshu + student3.dawu + student3.english;
	printf("输出学生成绩：\n");
    printf("%d %.1f %.1f %.1f %.1f", student1.num, student1.gaoshu, student1.dawu, student1.english, student1.sum);
	printf("\n");
	printf("%d %.1f %.1f %.1f %.1f", student2.num, student2.gaoshu, student2.dawu, student2.english, student2.sum);
	printf("\n");
	printf("%d %.1f %.1f %.1f %.1f" ,student3.num, student3.gaoshu, student3.dawu, student3.english, student3.sum);
    printf("\n");
	return 0;
}
第3步骤
#include<stdio.h>
int main(){
	char ch;
	int i; 
	for(i=1;i<=30;i++)
	printf(" ");
	printf("1.Input\n");
	 for(i=1;i<=30;i++)
	printf(" ");
	printf("2.Output\n");
	for(i=1;i<=30;i++)
	printf(" ");
	printf("3.Order\n");
	for(i=1;i<=30;i++)
	printf(" ");
	printf("4.Quit\n");
	scanf("%c",&ch);
	if(ch=='i'){
		printf("Please input info of the three students:\n");
	}
	else if(ch=='o'){
		printf("You are trying to Onput info\n");
	}
	else if(ch=='m'){
		printf("You are trying to Make things ordered\n");
	}
	else if(ch=='q'){
		printf("You are about to Quit\n");
	}
	else{
		printf("Wrong input");
	}
	struct student{
	    int num;
		float math;
		float phy;
		float eng;
	}stu[3];
	for(i=0;i<3;i++){
		scanf("%d%f%f%f",&stu[i].num,&stu[i].math,&stu[i].phy,&stu[i].eng);
	}
     float sum[3],aver[3];
     for(i=0;i<3;i++){
     	sum[i]=stu[i].math+stu[i].phy+stu[i].eng;
     	aver[i]=sum[i]/3;
	 }
	 float n[3];
	 int j;
	 n[0]=(sum[0]>sum[1]?sum[0]:sum[1]);
	 n[0]=(n[0]>sum[2]?n[0]:sum[2]);
	 if(n[0]==sum[0]){
	 	if(sum[1]>sum[2])
	 	{n[1]=sum[1];
	 	n[2]=sum[2];
		 }
		 else if(sum[2]>sum[1]){
		 	n[1]=sum[2];
		 	n[2]=sum[1];
		 }
	 }
	 else if(n[0]==sum[1]){
	 	if(sum[0]>sum[2]){
	 		n[1]=sum[0];
	 		n[2]=sum[2];
		 }
		 else if(sum[2]>sum[0]){
		 	n[1]=sum[2];
		 	n[2]=sum[0];
		 }
	 }
     else if(n[0]==sum[2]){
     	if(sum[0]>sum[1]){
     		n[1]=sum[0];
     		n[2]=sum[1];
		 }
		 else if(sum[1]>sum[0]){
		 	n[1]=sum[1];
		 	n[2]=sum[0];
		 }
	 }
	 for(i=2;i>=0;i--){
	 	for(j=0;j<3;j++){
	 		if(n[i]==sum[j])
	 			printf("%d,%.1f,%.1f\n",stu[j].num,sum[j],aver[j]);
		 }
	 }
    return 0;
}
第4步骤
#include<stdio.h>
#include<string.h>
typedef struct {
    char sid[10]; 
    int class; 
    float score[3]; 
    float totalScore; 
} Student;
void insertStudent(Student students[], int size, Student newStudent) {
    students[size] = newStudent;
    for (int i = 0; i < size; i++) {
        for (int j = i + 1; j <= size; j++) {
            if (students[i].class > students[j].class || (students[i].class == students[j].class && students[i].totalScore < students[j].totalScore)) {
                Student temp = students[i];
                students[i] = students[j];
                students[j] = temp;
            }
        }
    }
}
void printStudents(Student students[], int size,char insert[]) {
    char m;
    for (int i = 0; i < size; i++) {
        if(strcmp(students[i].sid,insert)==0)
        {
            printf(" %s %d %.1f %.1f %.1f %.1f insert\n", students[i].sid, students[i].class, students[i].score[0], students[i].score[1], students[i].score[2], students[i].totalScore);
        }
        else
        {
            printf(" %s %d %.1f %.1f %.1f %.1f\n", students[i].sid, students[i].class, students[i].score[0], students[i].score[1], students[i].score[2], students[i].totalScore);
        }
    }
}
int main() {
    Student students[4] = {
        {"1001", 11, {99.5,88.5,89.5}, 277.5},
        {"1002", 12, {77.9,56.5,87.5}, 221.9},
        {"1003", 11, {92.5,99.0,60.5}, 252.0}
    };
    int size = 3; 
	char insert[10];
    Student newStudent;
    printf("请输入新学生信息：\n");
    printf("学号：");
    scanf("%s\n", newStudent.sid);
    printf("班级：");
    scanf("%d\n", &newStudent.class);
    printf("三门课程成绩：");
    scanf("%f\n %f\n %f\n", &newStudent.score[0], &newStudent.score[1], &newStudent.score[2]);
	strcpy(insert,newStudent.sid);
    newStudent.totalScore = newStudent.score[0] + newStudent.score[1] + newStudent.score[2];
    insertStudent(students, size, newStudent);
    size++;
    printf("所有学生信息如下：\n");
    printStudents(students, size,insert);
    return 0;
}
第5步骤
#include<stdio.h>
#include<string.h>
#define N 3
struct stu_info
{
char num[20];
int cls,flag;
char name[20];
float math,physics,english,total;
}stu[N]={"10001",11,1,"Zhang",99.5,88.5,89.5,0,"10002",12,1,"Yang",77.9,56.5,87.5,0,"10003",11,1,"Liang",92.5,99.0,60.5,0};
void del(struct stu_info stu[],const char key[])
{
int i,exist=0,j;
struct stu_info t;
for(i=0;i<N;i++)
stu[i].total=stu[i].math+stu[i].physics+stu[i].english;
for(i=0;i<(N-1);i++){
for(j=i+1;j<N;j++){
if(stu[j].total>=stu[i].total)
              {t=stu[i];
              stu[i]=stu[j];
              stu[j]=t;
          }
           }
}
for (i=0;i<N;i++)
{   
if((strcmp((stu+i)->num,key)==0)||(strcmp((stu+i)->name,key)==0))
{
stu[i].flag=0;
exist=1;
}
}
int a;
    if(exist){
       for(a=11;a<=12;a++){
       	for(i=0;i<N;i++){
       		if(stu[i].flag&&stu[i].cls==a)
       		printf("%s %d %s %.1f %.1f %.1f\n",stu[i].num,stu[i].cls,stu[i].name,stu[i].math,stu[i].physics,stu[i].english);
		   }
}
}
else if(!exist){
for(i=0;i<N;i++)
printf("%s %d %s %.1f %.1f %.1f\n",stu[i].num,stu[i].cls,stu[i].name,stu[i].math,stu[i].physics,stu[i].english);
}

printf("Are you sure(yes/no)?\n");
char ch2;
scanf("%c",&ch2);
if(ch2=='y'){
return;
}
else if(ch2=='n'){
for(i=0;i<N;i++)
printf("%s %d %s %.1f %.1f %.1f\n",stu[i].num,stu[i].cls,stu[i].name,stu[i].math,stu[i].physics,stu[i].english);
}
}

int main()
{
	char key[20];
gets(key);
del(stu,key);
return 0;
}
第6步骤
#include<stdio.h>
#include<string.h> 
#define N 3

struct stu_info
{
	char num[20];
	int cls,flag;
	char name[20];
	float math,physics,english;
};

struct stu_info stu[N]={{"10001",11,0,"Zhang",99.5,88.5,89.5},
						{"10002",12,0,"Yang",77.9,56.5,87.5},
						{"10003",11,0,"Liang",92.5,99.0,60.5}};

void sort(struct stu_info *stu,int n)
{
	int i,j;
	struct stu_info tmp;
	for(i=0;i<n;i++)
	{
		for(j=0;j<n-i-1;j++)
		{
			if(((stu+j)->cls>(stu+j+1)->cls)||((stu+j)->cls==(stu+j+1)->cls)&&((stu+j)->num>(stu+j+1)->num))
			{
				tmp = *(stu+j);
				*(stu+j) = *(stu+j+1);
				*(stu+j+1) = tmp;
			} 
		}
	}
	return;
}

int main()
{
	struct stu_info mod;
	scanf("%s",&mod.num);
	scanf("%d",&mod.cls);
	scanf("%s",&mod.name);
	scanf("%f",&mod.math);
	scanf("%f",&mod.physics);
	scanf("%f",&mod.english);
	int i;
	for(i=0;i<N;i++)
	{
		if(strcmp(stu[i].num,mod.num)==0)
		{
			*(stu+i)=mod;
		}
	}
	sort(stu,N);
	for(i=0;i<N;i++)
	{
		if(i==0||stu[i].cls!=stu[i-1].cls) printf("%2d ",stu[i].cls);
		else printf("   "); 
		printf("%s %s %.1f %.1f %.1f",stu[i].num,stu[i].name,stu[i].math,stu[i].physics,stu[i].english);
		if(stu[i].flag) printf(" modified");
		printf("\n"); 
	}
	return 0;
}
第7步骤
#include<stdio.h>
#include<string.h>
struct student{
	int id;
	int class;
	char name[20];
	double score1;
	double score2;
	double score3;
	double score;
}stu[7]={10001,11,"Log",99.5,88.5,89.5,0,10002,12,"Yang",77.9,56.5,87.5,0,10003,11,"Liang",92.5,99.0,60.5,0,10004,11,"Cai",89.6,56.9,90.5,0,10005,14,"Fu",55.6,67.9,98.9,0,10006,12,"Mao",22.1,45.9,99.2,0,10007,13,"Zhan",35.6,67.9,88.0,0};
int main(){
	void solve1(void);
	void solve2(void);
	void solve3(void);
	void solve4(void);
	void solve5(void);
	int i,j;
	for(i=0;i<7;i++){
		stu[i].score=stu[i].score1+stu[i].score2+stu[i].score3;
	}
	scanf("%d",&j);
	if(j==1){
		solve1();
	}
	else if(j==2){
		solve2();
	}
	else if(j==3){
		solve3();
	}
	else if(j==4){
		solve4();
	}
	else if(j==5){
		solve5();
	}
return 0;
}
void solve1(void){
	int i,j,l,k=0,a,b,c,d;
	double *p;
	double *score[7];
	int *class[7];
	scanf("%d%d",&a,&b);
		for(c=a;c<=b;c++){
		k=0;
		for(i=0;i<7;i++){
			if(stu[i].class==c){
		score[k++]=&stu[i].score;
	}
	if(k==0);
	continue;
				}
	for(j=0;j<(k-1);j++){
			for(l=j+1;l<k;l++){
				if(*score[l]>*score[j])
				{
					p=score[j];
					score[j]=score[l];
					score[l]=p;
				}
				else
				continue;
			}
		}
	 for(i=0;i<k;i++){
	 	for(j=0;j<7;j++){
	 		if(*score[i]==stu[j].score){
	 			printf("%d %d %s %.1f %.1f %.1f\n",stu[j].id,stu[j].class,stu[j].name,stu[j].score1,stu[j].score2,stu[j].score3);
			 }
			 else
			 continue;
		 }
	 }
}
}
void solve2(void){
	 int i,j,k=0,l,a,b,c,d;
	 scanf("%d%d",&a,&b);
	 double *score[7];
	 double *p;
     for(i=11;i<=14;i++){
     	k=0;
     	for(j=0;j<7;j++){
     		if(stu[j].class==i&&(stu[j].id>=a&&stu[j].id<=b)){
     			score[k++]=&stu[j].score;
			 }
		 }
		 for(j=0;j<(k-1);j++){
		 	for(l=j+1;l<k;l++){
		 		if(*score[l]>*score[j]){
		 			p=score[j];
		 			score[j]=score[l];
		 			score[l]=p;
				 }
			 }
		 }
		 for(c=0;c<k;c++){
		 	for(d=0;d<7;d++){
		 		if(stu[d].score==*score[c])
		 			printf("%d %d %s %.1f %.1f %.1f\n",stu[d].id,stu[d].class,stu[d].name,stu[d].score1,stu[d].score2,stu[d].score3);
			 }
		 }
	 }
}
void solve3(void){
	 char ch[20]={'\0'};
	 int i,j,k=0,l,a,b,c;
	 char ch1;
	 scanf("%c",&ch1);
	 gets(ch);
	 int len,label=1;
	 double *score[7],*p;
	 len=strlen(ch);
	 for(i=0;i<7;i++){
	 	label=1;
	 	for(j=0;j<(len-1);j++){
	 		if(stu[i].name[j]!=ch[j])
	 		{
	 			label=0;
	 			break;
			 }
		 }
		 if(label==1)
		 score[k++]=&stu[i].score;
		 }
		 for(i=0;i<(k-1);i++){
		 	for(j=i+1;j<k;j++){
		 		if(*score[j]>=*score[i]){
		 			p=score[i];
		 			score[i]=score[j];
		 			score[j]=p;
				 }
			 }
		 }
		 for(i=11;i<=14;i++){
		 	for(j=0;j<k;j++){
		 		for(l=0;l<7;l++){
		 			if(stu[l].class==i&&stu[l].score==*score[j])
		 			printf("%d %d %s %.1f %.1f %.1f\n",stu[l].id,stu[l].class,stu[l].name,stu[l].score1,stu[l].score2,stu[l].score3);
				 }
			 }
		 }
		 
	 }
	 void solve4(void){
	 	int i,j,k,l,a,b,c,d;
	 	double *score[7],*p;
	 	for(i=0;i<7;i++){
	 		score[i]=&stu[i].score;
		 }
		 for(i=0;i<6;i++){
		 	for(j=i+1;j<7;j++){
		 		if(*score[j]>=*score[i]){
		 			p=score[i];
		 			score[i]=score[j];
		 			score[j]=p;
				 }
			 }
		 }
		 for(i=11;i<=14;i++){
		 	for(j=0;j<7;j++){
		 		for(l=0;l<7;l++){
		 			 if(stu[l].class==i&&*score[j]==stu[l].score&&stu[l].score>=98.0)
		 		printf("%d %d %s %.1f %.1f %.1f\n",stu[l].id,stu[l].class,stu[l].name,stu[l].score1,stu[l].score2,stu[l].score3);
				 }
			 }
		 }
	 }
void solve5(void){
	int i,j,k=0,l,a,b,c,d=0;
	double *score[7]={NULL},*p;
	char ch1,ch2;
	scanf("%d%d%d",&a,&b,&c);
	for(i=0;i<7;i++){
		if(stu[i].class==a&&(stu[i].id>=b&&stu[i].id<=c)){
			score[k++]=&stu[i].score;
		}
	}
	
	for(i=0;i<(k-1);i++){
		for(j=i+1;j<k;j++){
			if(*score[j]>=*score[i]){
				p=score[i];
				score[i]=score[j];
				score[j]=p;
			}
		}
	}
	     for(j=0;j<k;j++){
           for(l=0;l<7;l++){
           	if(stu[l].class==a&&stu[l].score==*score[j])
           	printf("%d %d %s %.1f %.1f %.1f\n",stu[l].id,stu[l].class,stu[l].name,stu[l].score1,stu[l].score2,stu[l].score3);
		   }
		 }
}
第8步骤
#include<stdio.h>
struct student{
	int id;
	int  class;
	char name[20];
	double score1;
	double score2;
	double score3;
	double score;
}stu[7];
void xunwen(void){
	printf("1.input\n");
	printf("2.delet\n");
	printf("3.select\n");
	printf("4.order\n");
	printf("5.output\n");
	printf("6.quit\n");
	printf("please input your option\n");
}
void input(void){
	 int i,j;
	 char str[3];
	 void zhixing(void);
	 for(i=0;i<7;i++){
	 		printf("id ");
	 		scanf("%d",&stu[i].id);
	 		printf("class ");
	 		scanf("%d",&stu[i].class);
	 		printf("name ");
	 		scanf("%s",stu[i].name);
	 		printf("score1 ");
	 		scanf("%lf",&stu[i].score1);
	 		printf("score2 ");
	 		scanf("%lf",&stu[i].score2);
	 		printf("score3 ");
	 		scanf("%lf",&stu[i].score3);
	 		printf("continue?\n");
	 		scanf("%s",str);
	 		if(str[0]=='y')
	 		continue;
	 		else if(str[0]=='n')
	 		break;
	 }
	 for(i=0;i<7;i++){
	 	stu[i].score=stu[i].score1+stu[i].score2+stu[i].score3;
	 }
	 xunwen();
	 zhixing();
}
void delet(struct student stu4[]){
	void xunwen(void);
	void zhixing(void);
	 int i,j,k,a,b,c;
	 char str[3];
	 scanf("%d",&a);
	 for(i=0;i<7;i++){
	 	if(stu[i].id==a){
          stu[i].id=0;
		 }
	 }
	 for(i=0;i<7;i++){
	 	if(stu[i].id!=0)
	 	printf("%d %d %s %.1f %.1f %.1f %.1f %.1f\n",stu[i].id,stu[i].class,stu[i].name,stu[i].score1,stu[i].score2,stu[i].score3,stu[i].score);
	 }
	 printf("continue?\n");
	 struct student *p=stu;
	 scanf("%s",str);
	 if(str[0]=='y')
	 delet(p);
	 else if(str[0]=='n')
	 xunwen();
	 zhixing();
}
void select(struct student stu7[]){
	 void xunwen(void);
	 void zhixing(void);
	 int i,j,k,a,b,c=1;
	 char str[3];
	 scanf("%d",&a);
	 if(a>100){
	 	for(i=0;i<7;i++){
	 		if(stu7[i].id==a)
	 		printf("%d %d %s %.1f %.1f %.1f %.1f\n",stu[i].id,stu[i].class,stu[i].name,stu[i].score1,stu[i].score2,stu[i].score3,stu[i].score);
	 		c=0;
		 }
	 }
	 else if(a<100){
	 	for(i=0;i<7;i++){
	 		if(stu7[i].class==a){
	 				printf("%d %d %s %.1f %.1f %.1f %.1f\n",stu[i].id,stu[i].class,stu[i].name,stu[i].score1,stu[i].score2,stu[i].score3,stu[i].score);
	 				c=0;
			 }	
	    }
	 }
	 if(c==1)
	 printf("there is no eligible student");
	 printf("continue?\n");
	 struct student *p=stu;
	 scanf("%s",str);
	 if(str[0]=='y'){
	 	select(p);
	 }
	 else if(str[0]=='n'){
	 	xunwen();
	 	zhixing();
	 }
}
void order(struct student stu2[]){
	void zhixing(void);
	void output(void);
     int i,j,k=0,a,b,c;
     struct student temp;
     struct student stu1[7];
     for(i=0;i<7;i++){
     	stu1[i]=stu2[i];
	 }
	 for(i=0;i<6;i++){
	 	for(j=i+1;j<7;j++){
	 		if(stu1[j].score>=stu1[i].score){
	 			temp=stu1[i];
	 			stu1[i]=stu1[j];
	 			stu1[j]=temp;
			 }
		 }
	 }
	 for(i=1;i<30;i++){
	 	for(j=0;j<7;j++){
	 		if(stu1[j].class==i)
	 		stu2[k++]=stu1[j];
		 }
	 }
  for(i=0;i<7;i++){
		if(stu[i].id!=0)
			printf("%d %d %s %.1f %.1f %.1f %.1f\n",stu[i].id,stu[i].class,stu[i].name,stu[i].score1,stu[i].score2,stu[i].score3,stu[i].score);
	}
	 xunwen();
	 zhixing();
}
void output(){
	void zhixing(void);
	int i;
	for(i=0;i<7;i++){
		if(stu[i].id!=0)
			printf("%d %d %s %.1f %.1f %.1f %.1f\n",stu[i].id,stu[i].class,stu[i].name,stu[i].score1,stu[i].score2,stu[i].score3,stu[i].score);
	}
	xunwen();
	zhixing();
}
void quit(void){
	return;
} 
void zhixing(void){
	int i;
	scanf("%d",&i);
	struct student *p=stu;
	 switch(i){
    	case 1:input();break;
    	case 2:delet(p);break;
    	case 3:select(p);break;
    	case 4:order(p);break;
    	case 5:output();break;
    	case 6:quit();break;
	}
}
int main(){
	xunwen();
	zhixing();
	return 0;
}