用c语言设计学生成绩管理系统，怎么写

设计学生成绩管理系统，需要考虑以下几个方面：

1. 数据结构：需要定义学生信息的结构体，包括学号、姓名、成绩等信息。

2. 数据存储：可以使用文件存储学生信息，也可以使用内存数据结构存储。

3. 功能实现：需要实现添加学生信息、删除学生信息、修改学生成绩、查询学生成绩等功能。

下面是一个简单的 C 语言学生成绩管理系统的实现代码：

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

#define Max 100

struct student
{
    char name[20];
    int num;
    float score;
}stu[Max];

int n;

void add();
void del();
void modify();
void query();
void display();

int main()
{
    int choice;

    while(1)
    {
        printf("\n");
        printf("|-----------------Student Grade Manage System-----------------|\n");
        printf("|                1.Add a record                             |\n");
        printf("|                2.Delete a record                          |\n");
        printf("|                3.Modify a record                          |\n");
        printf("|                4.Query a record                           |\n");
        printf("|                5.Display all records                      |\n");
        printf("|                6.Exit                                     |\n");
        printf("|------------------------------------------------------------|\n");
        printf("Please enter your choice:");

        scanf("%d",&choice);

        switch(choice)
        {
            case 1:
                add();
                break;
            case 2:
                del();
                break;
            case 3:
                modify();
                break;
            case 4:
                query();
                break;
            case 5:
                display();
                break;
            case 6:
                printf("You have exited the system!");
                exit(0);
            default:
                printf("Invalid input!");
        }
    }
    return 0;
}

void add()    //添加学生记录
{
    int i;
    printf("Please enter the number of students to be added:");
    scanf("%d",&n);

    for(i=0; i<n; i++)
    {
        printf("Please enter the information of student %d:\n",i+1);
        printf("Student name:");
        scanf("%s",stu[i].name);
        printf("Student number:");
        scanf("%d",&stu[i].num);
        printf("Student score:");
        scanf("%f",&stu[i].score);
    }

    printf("Add successfully!\n");
}

void del()    //删除学生记录
{
    int i,j,num;
    printf("Please enter the student number you want to delete:");
    scanf("%d",&num);

    for(i=0; i<n; i++)
    {
        if(stu[i].num==num)
        {
            for(j=i; j<n-1; j++)
            {
                stu[j]=stu[j+1];
            }
            n--;
            printf("Delete successfully!\n");
            return;
        }
    }

    printf("The student is not in the record!\n");
}

void modify()    //修改学生成绩
{
    int i,num;
    printf("Please enter the student number you want to modify:");
    scanf("%d",&num);

    for(i=0; i<n; i++)
    {
        if(stu[i].num==num)
        {
            printf("Please enter the new score:");
            scanf("%f",&stu[i].score);
            printf("Modify successfully!\n");
            return;
        }
    }

    printf("The student is not in the record!\n");
}

void query()    //查询学生成绩
{
    int i,num;
    printf("Please enter the student number you want to query:");
    scanf("%d",&num);

    for(i=0; i<n; i++)
    {
        if(stu[i].num==num)
        {
            printf("Student name:%s\n",stu[i].name);
            printf("Student number:%d\n",stu[i].num);
            printf("Student score:%.2f\n",stu[i].score);
            return;
        }
    }

    printf("The student is not in the record!\n");
}

void display()    //显示所有学生记录
{
    int i;
    printf("All student records are as follows:\n");

    for(i=0; i<n; i++)
    {
        printf("Student name:%s ",stu[i].name);
        printf("Student number:%d ",stu[i].num);
        printf("Student score:%.2f\n",stu[i].score);
    }
}

注意：这是一个简单的实现，数据存储使用内存数据结构，没有进行文件操作。实际应用中，需要根据具体需求进行修改。