求帮助改改我我运行的错误 5位学生4门课学生成绩管理系统

#include
#include
#define maxsize 5
struct student {
int num;
char name[30];
int english,computer,math,chinese;
int rank;

};
static float aen,aco,ama,ach;static int maxch,maxma,maxen,maxco,minch,minma,minen,minco,sum[5];
void menu (struct student students []);
void input_student (struct student students []);
void change_student (struct student *p);
void search_student (struct student *p);
void cal (struct student s[]);
void max (struct student s[]);
void min (struct student s[]);
void sort (struct student students[]);
void output_student (struct student students []);

void input_student (struct student students [])
{
int i;char ch;

for (i=0;i<5;i++){
printf("********************************\n");
printf("请输入：\n学号:");
scanf("%d",&students [i].num);
printf("姓名:");
scanf("%s",students [i].name);
printf("英语:");
scanf("%d",&students [i].english);
printf("计算机:");
scanf("%d",&students [i].computer);
printf("语文:");
scanf("%d",&students [i].math);
printf("数学:");
scanf("%d",&students [i].chinese);
printf("是否继续？（Y/N）________________:\n");
scanf("%c",&ch);

if (ch==('N'||'n')) break;}

return;

}

void output_student (struct student students [ ])
{
int i,a,b,j;int sum[5];

printf ("---------------------------------------------------------------------------\n");
printf ("num\t name\t english\t computer\t math\t chinese\t rank\n");
for (i=0;i<5;i++){

printf("%d\t",students [i].num);
printf(" %s\t",students [i].name);
printf(" %d\t",students [i].english);
printf(" %d\t",students [i].computer);
printf(" %d\t",students [i].math);
printf(" %d\t",students [i].chinese);
printf(" %d\t\n",students [i].rank);}

printf("平均分 %.2f\t%.2f\t%.2f\t%.2f\n",aen,aco,ama,ach);
printf("最高分 %d\t%d\t%d\t%d\n",maxen,maxco,maxma,maxch); /*分数的调用*/
printf("最低分 %d\t%d\t%d\t%d\n",minen,minco,minma,minch);
printf ("---------------------------------------------------------------------------");
return ;

}

void search_student (struct student students [ ] )
{

int i,cour,way,j;

char a[20];
printf("choice the way:1.姓名2.课程3.总分名次");
scanf("%d",&way);

switch(way){
case 1:
printf("姓名:");
scanf("%s",&a);
for (i=0;i<5;i++){
if (strcmp(students[i].name,a)==0) { /*逐个比较相等为0 ,不等返回不相等的差值 !strcmp(students[i].name, a)*/
printf(" num:%d",students [i].num);
printf(" english:%d",students [i].english);
printf(" computer:%d",students [i].computer);
printf(" math:%d",students [i].math);
printf("chinese:%d\n",students [i].chinese);}
}

case 2:printf("课程:");
printf("a-英语,b-计算机,c-数学,d-语文:");
scanf("%c",&cour);

if(cour=='a') {
printf(" 英语:");
for (i=0;i<5;i++) printf(" %d",students [i].english);
if(i==4) {
printf("平均分: %f",&aen);
printf(" 最高分:%d",&maxen);
printf("最低分: %d",&minen);}
}

if(cour=='b') {
printf(" 计算机:");
for (i=0;i<5;i++) printf(" %d",students [i].computer);
if(i==4) {
printf("平均分: %f",&aco);
printf(" 最高分:%d",&maxco);
printf("最低分: %d",&minco);}
}

if(cour=='c') {
printf(" 数学:");
for (i=0;i<5;i++) printf(" %d",students [i].math);
if(i==4) {
printf("平均分: %f",&ama);
printf(" 最高分:%d",&maxma);
printf("最低分: %d",&minma);}
}

if(cour=='d') {
printf("语文:");
for (i=0;i<5;i++) printf(" %d",students [i].chinese);
if(i==4) {
printf("平均分: %f",&ach);
printf(" 最高分:%d",&maxch);
printf("最低分: %d",&minch);}
}

case 3:for (j=1;j<6;j++)
for (i=0;i<5;i++)
if(students [i].rank==j) printf(" name:%s",students [i].name);

return;
}

}

void sort (struct student students[]){
int i,j,x;x=1;

for(i=0;i<5;i++)
for(j=1;i<6;i++)

if(sum[i]<sum[i+1])
{x=x+1;
students[i].rank=x;
}
return;
}

void max (struct student students []){
int i;

maxch=students [0].chinese;
maxma=students [0].math;
maxen=students [0].english;
maxco=students [0].computer;

for (i=0;i if (students [i].chinese>students [i+1].chinese){

maxch=students [i+1].chinese;}
if (students [i].math>students [i+1].math){

maxma=students [i+1].math;}
if (students [i].english>students [i+1].english){

maxen=students [i+1].english;}
if (students [i].computer>students [i+1].computer){

maxco=students [i+1].computer;}
}
return;
}

void min (struct student students []){
int i;

minch=students [0].chinese;
minma=students [0].math;
minen=students [0].english;
minco=students [0].computer;
/*各科最低*/
for (i=0;i<5;i++) {

if(students [i].chinese<students [i+1].chinese)
maxch=students [i+1].chinese;
if (students [i].math<students [i+1].math)

maxma=students [i+1].math;
if (students [i].english<students [i+1].english)

maxen=students [i+1].english;
if (students [i].computer<students [i+1].computer)

maxco=students [i+1].computer;}
return;
}

void change_student (struct student *p)
{
int num,course,score,i;
printf("输入学号:");
scanf("%d",&num);
printf("choice the course:1.english2.computer3.math4.chinese:");
scanf("%d",&course);
printf("输入新成绩:");
scanf("%d",&score);

for (i=0;i if(p->num==num)
break;
if(i switch(course)
{
case 1:p->english=score;break;
case 2:p->computer=score;break;
case 3:p->math=score;break;
case 4:p->chinese=score;break;
}
return;

}

int main (void){
struct student students[maxsize];
int c;

while (1){
printf("********************************\n");
printf(" 学生成绩管理系统\n");
printf("********************************\n");
printf(" （1）输入学生成绩\n");
printf(" （2）查询学生成绩\n");
printf(" （3）修改学生成绩\n");
printf(" （4）输出学生成绩\n");
printf(" （5）退出系统\n");
printf("请选择（1、2、3、4、5）______\n");
scanf("%d",&c);
if (c>5||c<0)
printf("error\n");
else
switch(c)
{
case 1:input_student (students);break;
case 2:search_student (students);break;
case 3:change_student (students);break;
case 4:output_student (students) ;
break;
case 5:break;
}
if (c==5) break;
}

return 0;
}

出现三个问题，第一，input 函数里yes or no 的选择不出现，第二，总分排须有问题，第三，我自定义函数里计算的值无法输出，不知道该怎么调用定义的cal,max,min.

求大神门帮助阿，用的是dev c++写的。

看看我的代码：
#if 1
#include
#include
#include
#define maxsize 5

struct student {
int num;
char name[30];
int english, computer, math, chinese;
int rank;
};
static float aen, aco, ama, ach; static int maxch, maxma, maxen, maxco, minch, minma, minen, minco, sum[5];
void menu(struct student students[]);
//void input_student(struct student students[]);
int input_student(struct student students[]);
void change_student(struct student p);
void search_student(struct student *p);
void cal(struct student s[]);
void max_(struct student s[]);
void min_(struct student s[]);
void sort(struct student students[]);
void output_student(struct student students[]);
void mnue();
int input_student(struct student students[])
{
int i; char ch;
for (i = 0; i<5; i++){
printf("*******************************\n");
printf("请输入：\n学号:");
scanf("%d", &students[i].num);
printf("姓名:");
scanf("%s", students[i].name);
printf("英语:");
scanf("%d", &students[i].english);
printf("计算机:");
scanf("%d", &students[i].computer);
printf("语文:");
scanf("%d", &students[i].math);
printf("数学:");
scanf("%d", &students[i].chinese);
printf("rank:");
scanf("%d", &students[i].rank);
printf("是否继续？（Y/N）________________:\n");
fflush(stdin);
scanf("%c", &ch);
//if (ch == ('N' || 'n'))
if (ch == 'N' || ch == 'n')
break;
//if (ch == ('Y' || 'y'))
if (ch == 'Y' || ch == 'y')
break;
}
return i+1;
}
void output_student(struct student students[], int n)
{
int i, a, b, j; int sum[5];
printf("---------------------------------------------------------------------------\n");
printf("num\tname\tenglish\tcomputer\tmath\tchinese\trank\n");
//此处必须得改变接口，因为数组名退化为指针，所以以下语句不能用。
//int aq = sizeof(students) / sizeof(students[0]);
for (i = 0; i printf(" %d\t", students[i].num);
printf(" %s\t", students[i].name);
printf(" %d\t", students[i].english);
printf(" %d\t\t", students[i].computer);
printf(" %d\t", students[i].math);
printf(" %d\t", students[i].chinese);
printf(" %d\t\n", students[i].rank);
}
printf("平均分 %.2f\t%.2f\t%.2f\t%.2f\n", aen, aco, ama, ach);
printf("最高分 %d\t%d\t%d\t%d\n", maxen, maxco, maxma, maxch); /*分数的调用*/
printf("最低分 %d\t%d\t%d\t%d\n", minen, minco, minma, minch);
printf("---------------------------------------------------------------------------");
//此处不要加return，加了return函数立即返回，并且你有没有要用返回值。并且记得清空缓存。
fflush(stdin);
getchar();
//return;
}
void search_student(struct student students[])
{
int i, cour, way, j;
char a[20];
printf("choice the way:1.姓名2.课程3.总分名次");
scanf("%d", &way);
switch (way){
case 1:
printf("姓名:");
scanf("%s", &a);
for (i = 0; i if (strcmp(students[i].name, a) == 0) { /*逐个比较相等为0 ,不等返回不相等的差值 !strcmp(students[i].name, a)*/
printf(" num:%d", students[i].num);
printf(" english:%d", students[i].english);
printf(" computer:%d", students[i].computer);
printf(" math:%d", students[i].math);
printf("chinese:%d\n", students[i].chinese);
}
}
case 2:printf("课程:");
printf("a-英语,b-计算机,c-数学,d-语文:");
scanf("%c", &cour);
if (cour == 'a') {
printf(" 英语:");
for (i = 0; i if (i == 4) {
//此处的输出有问题，怎么能给整型变量加&符呢？这样的话你输出的是地址。
//printf("平均分: %f", &aen);
printf(" 最高分:%d", &maxen);
printf("最低分: %d", &minen);
}
}
if (cour == 'b') {
printf(" 计算机:");
for (i = 0; i if (i == 4) {
printf("平均分: %f", &aco);
printf(" 最高分:%d", &maxco);
printf("最低分: %d", &minco);
}
}
if (cour == 'c') {
printf(" 数学:");
for (i = 0; i if (i == 4) {
printf("平均分: %f", &ama);
printf(" 最高分:%d", &maxma);
printf("最低分: %d", &minma);
}
}
if (cour == 'd') {
printf("语文:");
for (i = 0; i if (i == 4) {
printf("平均分: %f", &ach);
printf(" 最高分:%d", &maxch);
printf("最低分: %d", &minch);
}
}
case 3:for (j = 1; j for (i = 0; i if (students[i].rank == j) printf(" name:%s", students[i].name);
return;
}
}
void sort(struct student students[]){
int i, j, x; x = 1;
for (i = 0; i for (j = 1; i if (sum[i] {
x = x + 1;
students[i].rank = x;
}
return;
}
void max_(struct student students[])
{
int i;
maxch = students[0].chinese;
maxma = students[0].math;
maxen = students[0].english;
maxco = students[0].computer;
for (i = 0; i if (students[i].chinese>students[i + 1].chinese)
{
maxch = students[i + 1].chinese;
}
if (students[i].math>students[i + 1].math)
{
maxma = students[i + 1].math;
}
if (students[i].english>students[i + 1].english)
{
maxen = students[i + 1].english;
}
if (students[i].computer>students[i + 1].computer)
{
maxco = students[i + 1].computer;
}
}

void min_(struct student students[]){
int i;
minch = students[0].chinese;
minma = students[0].math;
minen = students[0].english;
minco = students[0].computer;
/*各科最低*/
for (i = 0; i if (students[i].chinese maxch = students[i + 1].chinese;
if (students[i].math maxma = students[i + 1].math;
if (students[i].english maxen = students[i + 1].english;
if (students[i].computer maxco = students[i + 1].computer;
}
return;
}
void change_student(struct student *p)
{
int num, course, score, i;
printf("输入学号:");
scanf("%d", &num);
printf("choice the course:1.english2.computer3.math4.chinese:");
scanf("%d", &course);
printf("输入新成绩:");
scanf("%d", &score);
for (i = 0; i if (p->num == num)
break;
switch (course)
{
case 1:p->english = score; break;
case 2:p->computer = score; break;
case 3:p->math = score; break;
case 4:p->chinese = score; break;
}
}

void mnue()
{
printf("********************************\n");
printf(" 学生成绩管理系统\n");
printf("********************************\n");
printf(" （1）输入学生成绩\n");
printf(" （2）查询学生成绩\n");
printf(" （3）修改学生成绩\n");
printf(" （4）输出学生成绩\n");
printf(" （5）退出系统\n");
printf("请选择（1、2、3、4、5）______\n");
}

int main(void){
struct student students[maxsize];
int c, a;
while (1){
system("cls");
mnue();
scanf("%d", &c);
if (c>5 || c<0)
printf("error\n");
else
switch (c)
{
case 1:a = input_student(students); break;
case 2:search_student(students); break;
case 3:change_student(students); break;
case 4:output_student(students, a); break;
case 5:break;
}
}
return 0;
}
#endif
代码逻辑错误很多，但是我改了一部分。

http://www.doc88.com/p-382731888369.html

粘贴错误很多，修改一下，把代码放到代码片里。
看到一处错误，修改如下：

 void input_student (struct student students [])
{
    int i;char ch;
    for (i=0;i<5;i++){
        printf("********************************\n");
        printf("请输入：\n学号:");
        scanf("%d",&students [i].num);
        printf("姓名:");
        scanf("%s",students [i].name);
        printf("英语:");
        scanf("%d",&students [i].english);
        printf("计算机:");
        scanf("%d",&students [i].computer);
        printf("语文:");
        scanf("%d",&students [i].math);
        printf("数学:");
        scanf("%d",&students [i].chinese);
        printf("是否继续？（Y/N）________________:\n");
        scanf("%c",&ch);
        if (ch=='N' || ch=='n') break;}//修改
    return;
}

![图片说明](https://img-ask.csdn.net/upload/201512/29/1451368198_988692.png)图片说明

图片说明

我把平均分去了，看看截图...
![图片说明](https://img-ask.csdn.net/upload/201512/29/1451369915_235008.png)图片说明

图片说明
#if 1
#include
#include
#include
#define maxsize 5

max_(students, n);
min_(students, n);
//此处以下三条语句中的变量输出一定是0， 因为此时你并没有给他们赋值。
/*printf("平均分 %.2f\t%.2f\t%.2f\t%.2f\n", aen, aco, ama, ach);
printf("最高分 %d\t%d\t%d\t%d\n", maxen, maxco, maxma, maxch); 
printf("最低分 %d\t%d\t%d\t%d\n", minen, minco, minma, minch);*/
printf("---------------------------------------------------------------------------");
//此处不要加return， 加了return函数立即返回，并且你有没有要用返回值。并且记得清空缓存。
fflush(stdin);
getchar();
//return;

}
void search_student(struct student students[])
{
int i, cour, way, j;
char a[20];
printf("choice the way:1.姓名2.课程3.总分名次");
scanf("%d", &way);
switch (way){
case 1:
printf("姓名:");
scanf("%s", a);
for (i = 0; i if (strcmp(students[i].name, a) == 0) { /*逐个比较相等为0 ,不等返回不相等的差值 !strcmp(students[i].name, a)*/
printf(" num:%d", students[i].num);
printf(" english:%d", students[i].english);
printf(" computer:%d", students[i].computer);
printf(" math:%d", students[i].math);
printf("chinese:%d\n", students[i].chinese);
}
}
case 2:printf("课程:");
printf("a-英语,b-计算机,c-数学,d-语文:");
scanf("%c", &cour);
if (cour == 'a') {
printf(" 英语:");
for (i = 0; i if (i == 4) {
//此处的输出有问题，怎么能给整型变量加&符呢？这样的话你输出的是地址。
//printf("平均分: %f", &aen);
//printf(" 最高分:%d", &maxen);
//printf("最低分: %d", &minen);
printf("平均分: %f", aen);
printf(" 最高分:%d", maxen);
printf("最低分: %d", minen);
}
}
if (cour == 'b') {
printf(" 计算机:");
for (i = 0; i if (i == 4) {
/*printf("平均分: %f", &aco);
printf(" 最高分:%d", &maxco);
printf("最低分: %d", &minco);*/
printf("平均分: %f", aco);
printf(" 最高分:%d", maxco);
printf("最低分: %d", minco);
}
}
if (cour == 'c') {
printf(" 数学:");
for (i = 0; i if (i == 4) {
/*printf("平均分: %f", &ama);
printf(" 最高分:%d", &maxma);
printf("最低分: %d", &minma);*/
printf("平均分: %f", ama);
printf(" 最高分:%d", maxma);
printf("最低分: %d", minma);
}
}
if (cour == 'd') {
printf("语文:");
for (i = 0; i if (i == 4) {
/*printf("平均分: %f", &ach);
printf(" 最高分:%d", &maxch);
printf("最低分: %d", &minch);*/
printf("平均分: %f", ach);
printf(" 最高分:%d", maxch);
printf("最低分: %d", minch);
}
}
case 3:for (j = 1; j for (i = 0; i if (students[i].rank == j) printf(" name:%s", students[i].name);
return;
}
}
void sort(struct student students[]){
int i, j, x; x = 1;
for (i = 0; i for (j = 1; i if (sum[i] {
x = x + 1;
students[i].rank = x;
}
return;
}
void max_(struct student students[], int n)
{
int i;
maxch = students[0].chinese;
maxma = students[0].math;
maxen = students[0].english;
maxco = students[0].computer;
for (i = 0; i {
/* if (students[i].chinese > students[i + 1].chinese)
{
maxch = students[i + 1].chinese;
}
if (students[i].math > students[i + 1].math)
{
maxma = students[i + 1].math;
}
if (students[i].english > students[i + 1].english)
{
maxen = students[i + 1].english;
}
if (students[i].computer > students[i + 1].computer)
{
maxco = students[i + 1].computer;
}*/

    if (maxch <= students[i].chinese)
    {
        maxch = students[i].chinese;
    }
    if (maxma <= students[i].math)
    {
        maxma = students[i].math;
    }
    if (maxen <= students[i].english)
    {
        maxen = students[i].english;
    }
    if (maxco <= students[i].computer)
    {
        maxco = students[i].computer;
    }
}
    printf("最高分 %d\t%d\t%d\t%d\n", maxen, maxco, maxma, maxch);

}

void min_(struct student students[], int n){
int i;
minch = students[0].chinese;
minma = students[0].math;
minen = students[0].english;
minco = students[0].computer;
/*各科最低*/
for (i = 0; i {
//此处已经改过了...
if (minch >= students[i].chinese)
maxch = students[i].chinese;
if (minma >= students[i].math)
maxma = students[i].math;
if (minen >= students[i].english)
maxen = students[i].english;
if (minco >= students[i].computer)
maxco = students[i].computer;
}
printf("最低分 %d\t%d\t%d\t%d\n", minen, minco, minma, minch);
}
void change_student(struct student *p)
{
int num, course, score, i;
printf("输入学号:");
scanf("%d", &num);
printf("choice the course:1.english2.computer3.math4.chinese:");
scanf("%d", &course);
printf("输入新成绩:");
scanf("%d", &score);
for (i = 0; i if (p->num == num)
break;
switch (course)
{
case 1:p->english = score; break;
case 2:p->computer = score; break;
case 3:p->math = score; break;
case 4:p->chinese = score; break;
}
}

 #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define maxsize 5
struct student {
int num;
char name[30]; 
int english,computer,math,chinese;
int rank;
};
double aen,aco,ama,ach;int maxch,maxma,maxen,maxco,minch,minma,minen,minco,sum[5],k;
//void menu (struct student students []);
void input_student (struct student students []);
void change_student (struct student *p);
void search_student (struct student *p);
void cal (struct student s[]);
void max (struct student s[]);
void min (struct student s[]);
void sort (struct student students[]);
void output_student (struct student students []);

void input_student (struct student students [])
{
int i;
for (i=0;i<5;i++){
printf("********************************\n");
printf("请输入：\n学号:");
scanf_s("%d",&students [i].num);getchar();
printf("姓名:");
scanf_s("%s",students [i].name,30);getchar();
printf("英语:");
scanf_s("%d",&students [i].english);getchar();
printf("计算机:");
scanf_s("%d",&students [i].computer);getchar();
printf("数学:");
scanf_s("%d",&students [i].math);getchar();
printf("语文:");
scanf_s("%d",&students [i].chinese);getchar();
}
max (students);
min (students);
cal (students);
sort(students);
}

void output_student (struct student students [ ]) 
{
int i;
printf ("---------------------------------------------------------------------------\n");
printf ("num\t name\t engl\t comp\t math\t chin\t rank\n");
for (i=0;i<5;i++){
printf("%d\t",students [i].num);
printf(" %s\t",students [i].name);
printf(" %d\t",students [i].english);
printf(" %d\t",students [i].computer);
printf(" %d\t",students [i].math);
printf(" %d\t",students [i].chinese);
printf(" %d\t\n",students [i].rank);}
printf("平均分    \t%.1f\t%.1f\t%.1f\t%.1f\n",aen,aco,ama,ach);
printf("最高分    \t%d\t%d\t%d\t%d\n",maxen,maxco,maxma,maxch); /*分数的调用*/ 
printf("最低分    \t%d\t%d\t%d\t%d\n",minen,minco,minma,minch);
printf ("---------------------------------------------------------------------------");
}

void search_student (struct student students [ ] ) 
{
int i,way,j;
char a[20],cour;
printf("choice the way:1.姓名2.课程3.总分名次");
scanf_s("%d",&way);getchar();
switch(way){
case 1:
printf("姓名:");
scanf_s("%s",a,20);getchar();
for (i=0;i<5;i++){
if (strcmp(students[i].name,a)==0) { /*逐个比较相等为0 ,不等返回不相等的差值 !strcmp(students[i].name, a)*/ 
printf(" num:%d",students [i].num);
printf(" english:%d",students [i].english);
printf(" computer:%d",students [i].computer);
printf(" math:%d",students [i].math);
printf("chinese:%d\n",students [i].chinese);}
}

case 2:printf("课程:");
printf("a-英语,b-计算机,c-数学,d-语文:");
scanf_s("%c",&cour);
if(cour=='a') {
printf(" 英语:");
for (i=0;i<5;i++) printf(" %d",students [i].english);
printf("平均分: %f",aen);
printf(" 最高分:%d",maxen);
printf("最低分: %d",minen);
}

if(cour=='b') {
printf(" 计算机:");
for (i=0;i<5;i++) printf(" %d",students [i].computer);
printf("平均分: %f",aco);
printf(" 最高分:%d",maxco);
printf("最低分: %d",minco);
}

if(cour=='c') {
printf(" 数学:");
for (i=0;i<5;i++) printf(" %d",students [i].math);
printf("平均分: %f",ama);
printf(" 最高分:%d",maxma);
printf("最低分: %d",minma);
}

if(cour=='d') {
printf("语文:");
for (i=0;i<5;i++) printf(" %d",students [i].chinese);
printf("平均分: %f",ach);
printf(" 最高分:%d",maxch);
printf("最低分: %d",minch);
}

case 3:
for (j=1;j<6;j++)
for (i=0;i<5;i++)
if(students [i].rank==j) printf(" name:%s",students [i].name);
return; 
}
}

void sort (struct student students[]){
int i,j,x,maxsum;x=1;
for(i=0;i<5;i++)
    sum[i]=students[i].chinese+students[i].math+
    students[i].computer+students[i].english;
for(i=0;i<5;i++)
    students[i].rank=0;
for(i=0;i<5;i++)
{
    if(students[i].rank==0)
    {
        maxsum=sum[i]; k=i;
        for(j=0;j<5;j++)
        {
            if(students[j].rank==0)
                if(sum[j]>maxsum)
                {
                    maxsum=sum[j]; k=j;
                }
        }
        students[k].rank=x;  x++;
    }
}
for(i=0;i<5;i++)
    if(students[i].rank==0)
    {
        k=i;  students[k].rank=x;
    }
}

void max (struct student students []){
int i;
maxch=students [0].chinese;
maxma=students [0].math;
maxen=students [0].english;
maxco=students [0].computer;
for (i=1;i<5;i++) {
if (students [i].chinese>maxch){
maxch=students [i].chinese;}
if (students [i].math>maxma){
maxma=students [i].math;}
if (students [i].english>maxen){
maxen=students [i].english;}
if (students [i].computer>maxco){
maxco=students [i].computer;}
}
}

void min (struct student students []){
int i;
minch=students [0].chinese;
minma=students [0].math;
minen=students [0].english;
minco=students [0].computer;
/*各科最低*/ 
for (i=1;i<5;i++) {
if(students [i].chinese<minch)
minch=students [i].chinese;
if (students [i].math<minma)
minma=students [i].math;
if (students [i].english<minen)
minen=students [i].english;
if (students [i].computer<minco)
minco=students [i].computer;}
}

void cal (struct student students[])
{
    int i;double tach=0,tama=0,taen=0,taco=0;
    for(i=0;i<5;i++)
    {
        tach+=students[i].chinese;
        tama+=students[i].math;
        taen+=students[i].english;
        taco+=students[i].computer;
    }
    ach=tach/5; ama=tama/5; aen=taen/5; aco=taco/5;
}

void change_student (struct student *p) 
{
int num,course,score,i;
printf("输入学号:");
scanf_s("%d",&num);
printf("choice the course:1.english2.computer3.math4.chinese:");
scanf_s("%d",&course);
printf("输入新成绩:");
scanf_s("%d",&score);
for(i=0;i<5;i++,p++){
if(p->num==num)
switch(course)
{
case 1:p->english=score;break;
case 2:p->computer=score;break;
case 3:p->math=score;break;
case 4:p->chinese=score;break;
}
}
}

int main (void){
struct student students[maxsize];
int c;
while (1){
printf("********************************\n");
printf(" 学生成绩管理系统\n");
printf("********************************\n");
printf(" （1）输入学生成绩\n");
printf(" （2）查询学生成绩\n");
printf(" （3）修改学生成绩\n");
printf(" （4）输出学生成绩\n");
printf(" （5） 退出系统\n");
printf("请选择（1、2、3、4、5）______\n");
scanf_s("%d",&c);getchar();
if (c>5||c<1)
printf("error\n");
else 
switch(c)
{
case 1:input_student (students);break;
case 2:search_student (students);break;
case 3:change_student (students);break;
case 4:output_student (students) ;break;
case 5:break;
}
if(c==5)
    break;
}
system("pause");
return 0;
}