关于#c语言#的问题，请各位专家解答！

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define Max 30

int Menu(void);
void Readscore(float score[], long ID[], int n,char name[][21]);
void Average(float socore[], int n);
void Scoreuprand(float score[], long ID[], char name[][21], int n);
void IDfind(float score[], long ID[], char name[][21], int n);
void Namefind(float score[], long ID[], char name[][21], int n);
void Verious(float score[], int n);
void Mingzi(char name[], char m[]);
void Xuehao(long* px, long* py);
void Fenshu(float* px, float* py);
void Chengjidan(float score[], long ID[], char name[][21],int n);
int main()
{
    int x;
    int n;
    char name[Max][21];
    float score[Max];
    long ID[Max];
    
    printf("****************************************\n");
    printf("*         欢迎使用学生管理系统         *\n");
    printf("****************************************\n");
    printf("请输入所在班级人数：");
    scanf_s("%d", &n);
    getchar();
    while (1)
    {
        x = Menu();
        switch (x)
        {
        case 1: Readscore(score, ID, n, name);   break;
        case 2: Average(score, n);               break;
        case 3: Scoreuprand(score, ID, n, name); break;
        case 4: IDfind(score, ID, n, name);      break;
        case 5: Namefind(score, ID, n, name);    break;
        case 6: Verious(score, n);               break;
        case 7: Chengjidan(score, ID, name, n);  break;
        case 0: return 0;                        break;
        default:printf("输入错误，请重新输入！");
        }
    }
}
int Menu(void)
{
    int x;
    system("cls");
    printf("****************************************\n");
    printf("*********欢迎使用学生成绩管理系统*******\n");
    printf("*                 菜单                 *\n");
    printf("*            1.录入成绩                *\n");
    printf("*            2.总成绩与平均分          *\n");
    printf("*            3.分数按降序排列          *\n");
    printf("*            4.按学号查询成绩          *\n");
    printf("*            5.按姓名查询成绩          *\n");
    printf("*            6.成绩分析                *\n");
    printf("*            7.成绩单                  *\n");
    printf("*            0.退出                    *\n");
    printf("*            请输入你的选择:           *\n");
    printf("****************************************\n");
    scanf("%d", &x);
    return x;
}

void Readscore(float score[], long ID[], int n, char name[][21])
{
    system("cls");
    printf("*               成绩录入               *\n");
    int i;
    printf("输入学号，姓名和成绩：\n");
    for (i = 0; i < n; i++)
    {
        //gets(ID[i], name[i], score[i]);
        scanf("%1D %s %f", &ID[i], name+i, &score[i]);
    }
    system("pause");
}

void Average(float score[], int n)
{
    system("cls");
    printf("*              总分和平均分              *\n");
    int i, sum = 0;
    for (i = 0; i < n; i++)
    {
        sum += score[i];
    }
    printf("*    成绩总和:%d    成绩平均分:%d     *\n", sum, sum / (float)n);
    system("pause");
}

void Scoreuprand(float score[], long ID[], char name[][21], int n)
{
    system("cls");
    printf(" *                 成绩表               * \n");
    int i, j;
    for (i = 0; i < n; i++)
    {
        for (j = i + 1; j < n; j++)
        {
            if (score[i]>score[j])
            {
                Fenshu(&score[i], &score[j]);
                Mingzi(name[i], name[j]);
                Xuehao(&ID[i], &ID[j]);
            }
        }
    }
    Chengjidan(score, ID, name, n);
    system("pause");
}

void IDfind(float score[], long ID[], char name[][21], int n)
{
    system("cls");
    printf("*               学号查询               *\n");
    int low = 0, high = n - 1, ret,i, k;
    printf("*请输入要查询的学生学号:*\n");
    ret=scanf("%1d", &k);
    while (ret != 1)
    {
        while (getchar() != '\n');
        printf("*请输入正确的学号：*\n");
        scanf("%1d", &k);
    }
    for (i = 0; i < n; i++)
    {
        if (k == ID[i])
        {
            printf("查询结果：\n");
            printf("\n学号：%1d ",ID[i]);
            printf("姓名; %s  ",name[i]);
            printf("成绩：%f\n",score[i]);
            break;
        }
        if (k == (n - 1) && k != ID[i])
        {
            printf("未找到该同学，请重新输入学号\n");
        }
    }
    system("pause");
}

void Namefind(float score[], long ID[], char name[][21], int n)
{
    system("cls");
    printf("*               姓名查询               *\n");
    long i = 0;
    char cha[11];
    char chu[11] = "0";
    while (1)
    {
        printf("请输入需要查询的姓名：\n");
        scanf("%s", cha);
        if (strcmp(cha, chu) == 0)
        {
            printf("即将返回主菜单\n");
            return (0);
        }
        for (i = 0; i < n; i++)
        {
            if (strcmp(cha, name[i]) == 0)
            {
                printf("姓名：%s", name[i]);
                printf("学号：%1d", ID[i]);
                printf("成绩：%f\n", score[i]);
                break;
            }
            if (i == (n - 1) && strcmp(cha, name[i]) != 0)
            {
                printf("未找到该同学，请重新输入姓名\n");
            }
        }
        system("pause");
    }
}

void Verious(float score[], int n)
{
    system("cls");
    printf("*                成绩分类               *\n");
    int i;
    float x1 = 0, x2 = 0, x3 = 0, x4 = 0, x5 = 0;
    for (i = 0; i < n; i++)
    {
        if (score[i] >= 90 && score[i]<=100)
        {
            x1++;
        }
        else if (score[i] >= 80 && score[i]<=90)
        {
            x2++;
        }
        else if (score[i] >= 70 && score[i]<=80)
        {
            x3++;
        }
        else if (score[i] >= 60 && score[i]<=70)
        {
            x4++;
        }
        else
        {
            x5++;
        }
    }
    printf("优秀人数：   %.f");
    printf("良好人数:    %.f");
    printf("较好人数：   %.f");
    printf("及格人数：   %.f");
    printf("不及格人数： %.f");
    system("pause");
}

void Mingzi(char name[], char m[])
{
    char s[21];
    strcpy(s, name);
    strcpy(name, m);
    strcpy(m, s);
}

void Xuehao(long* px, long* py)
{
    int x;
    x = *px;
    *px = *py;
    *py = x;
}

void Fenshu(float* px, float* py)
{
    int x;
    x = *px;
    *px = *py;
    *py = x;
}

void Chengjidan(float score[], long ID[], char name[][21], int n)
{
    int i;
    if (n == 0)
    {
        printf("未录入成绩！");
    }
    printf("姓名          学号          分数\n");
    for (i = 0; i < n; i++)
    {
        printf("%d   %d   %d   %d\n",i+1,name[i],ID[i],score[i]);
    }
    system("pause");
}

本来是真心不想给你改这个程序的，里面好多基本规则都没有遵守，后面还是给你修改了。
都验证可以的，源码如下：

#include    <stdio.h>
#include    <string.h>
#include    <stdlib.h>
#define Max 30
 
typedef struct
{
    char name[21];
    double score;
    char ID[21];
}Student_Struct;

int Menu(void);

void Readscore(Student_Struct *student,int n);
void Average(Student_Struct *student, int n);
void Scoreuprand(Student_Struct *student, int n);
void Chengjidan(Student_Struct *student, int n);
void IDfind(Student_Struct *student, int n);
void Namefind(Student_Struct *student, int n);
void Verious(Student_Struct *student, int n);


int main()
{
    int x;
    int n;
    //char name[Max][21];
    //float score[Max];
    //long ID[Max];
    Student_Struct student_structure[Max];
    
    printf("****************************************\n");
    printf("*         欢迎使用学生管理系统         *\n");
    printf("****************************************\n");
    printf("请输入所在班级人数：");
    scanf("%d", &n);
    //getchar();
    while (1)
    {
        x = Menu();

        switch (x)
        {
        case 1: 
                Readscore(student_structure, n);   
                break;
        case 2: 
                Average(student_structure, n);               
                break;
        case 3: 
                Scoreuprand(student_structure, n);
                break;
        case 4: 
                IDfind(student_structure, n);      
                break;
        case 5: 
                Namefind(student_structure, n);  
                break;
        case 6: 
                Verious(student_structure, n);             
                break;
        case 7: 
                Chengjidan(student_structure, n);
                //Chengjidan(score, ID, name, n);  
                break;
        case 0: 
                return 0;                        
                break;
        default:
                printf("输入错误，请重新输入！");
                break;
        }

    }
}
int Menu(void)
{
    int x;
    system("cls");
    printf("****************************************\n");
    printf("*********欢迎使用学生成绩管理系统*******\n");
    printf("*                 菜单                 *\n");
    printf("*            1.录入成绩                *\n");
    printf("*            2.总成绩与平均分          *\n");
    printf("*            3.分数按升序排列          *\n");
    printf("*            4.按学号查询成绩          *\n");
    printf("*            5.按姓名查询成绩          *\n");
    printf("*            6.成绩分析                *\n");
    printf("*            7.成绩单                  *\n");
    printf("*            0.退出                    *\n");
    printf("*            请输入你的选择:           *\n");
    printf("****************************************\n");
    scanf("%d", &x);
    return x;
}
void Readscore(Student_Struct *student,int n)
{
    system("cls");
    printf("*               成绩录入               *\n");
    int i;
    printf("输入学号，姓名和成绩：\n");
    for (i = 0; i < n; i++)
    {
        scanf("%s %s %lf", student[i].ID, student[i].name, &student[i].score);
    }
    system("pause");
}


void Average(Student_Struct *student, int n)
{
    system("cls");
    printf("*              总分和平均分              *\n");
    int i;
    double sum = 0;
    for (i = 0; i < n; i++)
    {
        sum += student[i].score;
    }
    printf("*    成绩总和:%lf    成绩平均分:%lf    *\n", sum, sum / n);
    system("pause");
}

void Mingzi(char *name, char *m)
{
    char s[21];
    strcpy(s, name);
    strcpy(name, m);
    strcpy(m, s);
}
 
void Xuehao(char *px, char *py)
{
    char s[21];

    strcpy(s, px);
    strcpy(px, py);
    strcpy(py, s);
   
}
 
void Fenshu(double *px, double *py)
{
    double x;
    x = *px;
    *px = *py;
    *py = x;
}
void Chengjidan(Student_Struct *student, int n)
{
    int i;
    if (n == 0)
    {
        printf("未录入成绩！");
    }
    printf("     姓名          学号          分数\n");
    for (i = 0; i < n; i++)
    {
        printf("%d   %s   %s   %lf\n",i+1,student[i].name,student[i].ID,student[i].score);
    }
    system("pause");
}
void Scoreuprand(Student_Struct *student, int n)
{
    int i, j;
    system("cls");
    printf(" *                 成绩表               * \n");
    
    for (i = 0; i < n; i++)
    {
        for (j = i + 1; j < n; j++)
        {
            if (student[i].score>student[j].score)
            {
                Fenshu(&student[i].score, &student[j].score);
                Mingzi(student[i].name, student[j].name);
                Xuehao(student[i].ID, student[j].ID);
            }
        }
    }
    Chengjidan(student, n);
    system("pause");
}

void IDfind(Student_Struct *student, int n)
{
    int low = 0, high = n - 1, ret,i;
    char k[21];
    system("cls");
    printf("*               学号查询               *\n");
    

    printf("*请输入要查询的学生学号:*\n");
    ret=scanf("%s", k);
    /*
    while (ret != 1)
    {
        while (getchar() != '\n');
        printf("*请输入正确的学号：*\n");
        scanf("%1d", &k);
    }
    */
    for (i = 0; i < n; i++)
    {
        if (strcmp(k,student[i].ID)==0)
        {
            printf("查询结果：\n");
            printf("\n学号:%s ",student[i].ID);
            printf("姓名; %s  ",student[i].name);
            printf("成绩：%f\n",student[i].score);
            break;
        }
        if (i == (n - 1))
        {
            printf("未找到该同学，请重新输入学号\n");
        }
    }
    system("pause");
}

void Namefind(Student_Struct *student, int n)
{
    system("cls");
    printf("*               姓名查询               *\n");
    long i = 0;
    char name[21];
    char chu[21] = "0";
    while (1)
    {
        printf("请输入需要查询的姓名：\n");
        scanf("%s", name);
        if (strcmp(name, chu) == 0)
        {
            printf("即将返回主菜单\n");
            return (0);
        }
        for (i = 0; i < n; i++)
        {
            if (strcmp(name, student[i].name) == 0)
            {
                printf("姓名：%s", student[i].name);
                printf("学号：%s", student[i].ID);
                printf("成绩：%lf\n", student[i].score);
                break;
            }
            if (i == (n - 1))
            {
                printf("未找到该同学，请重新输入姓名\n");
            }
        }
        system("pause");
    }
}

void Verious(Student_Struct *student, int n)
{
    system("cls");
    printf("*                成绩分类               *\n");
    int i;
    int x1 = 0, x2 = 0, x3 = 0, x4 = 0, x5 = 0;
    for (i = 0; i < n; i++)
    {
        if (student[i].score >= 90 && student[i].score<=100)
        {
            x1++;
        }
        else if (student[i].score >= 80)
        {
            x2++;
        }
        else if (student[i].score >= 70)
        {
            x3++;
        }
        else if (student[i].score >= 60)
        {
            x4++;
        }
        else
        {
            x5++;
        }
    }
    printf("优秀人数：   %d\n",x1);
    printf("良好人数:    %d\n",x2);
    printf("较好人数：   %d\n",x3);
    printf("及格人数：   %d\n",x3);
    printf("不及格人数： %d\n",x4);
    system("pause");
}

遇到了什么问题？

这种管理系统，你找GPT随便生成的，都可以用。