用函数调用改写学生成绩 c语言

将学生成绩的记录存储到一个结构体数组中，每个结构体包含学生的姓名、学号和成绩等信息。然后通过函数调用实现对学生成绩的操作，例如添加新的学生成绩、删除已有的学生成绩、查询某个学生的成绩、计算所有学生的平均成绩等。以下是一个简单的示例代码：

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

#define MAX_STUDENTS 100

struct student {
    char name[20];
    int id;
    float score;
};

struct student students[MAX_STUDENTS];
int num_students = 0;

void add_student() {
    if (num_students >= MAX_STUDENTS) {
        printf("Error: too many students!\n");
        return;
    }
    struct student s;
    printf("Enter student name: ");
    scanf("%s", s.name);
    printf("Enter student id: ");
    scanf("%d", &s.id);
    printf("Enter student score: ");
    scanf("%f", &s.score);
    students[num_students] = s;
    num_students++;
}

void delete_student() {
    int id;
    printf("Enter student id to delete: ");
    scanf("%d", &id);
    int i;
    for (i = 0; i < num_students; i++) {
        if (students[i].id == id) {
            break;
        }
    }
    if (i == num_students) {
        printf("Error: student not found!\n");
        return;
    }
    for (; i < num_students - 1; i++) {
        students[i] = students[i + 1];
    }
    num_students--;
}

void print_student(struct student s) {
    printf("%-20s %-10d %6.2f\n", s.name, s.id, s.score);
}

void query_student() {
    int id;
    printf("Enter student id to query: ");
    scanf("%d", &id);
    int i;
    for (i = 0; i < num_students; i++) {
        if (students[i].id == id) {
            print_student(students[i]);
            return;
        }
    }
    printf("Error: student not found!\n");
}

void print_all_students() {
    int i;
    printf("%-20s %-10s %s\n", "Name", "ID", "Score");
    for (i = 0; i < num_students; i++) {
        print_student(students[i]);
    }
}

float average_score() {
    if (num_students == 0) {
        printf("Error: no students!\n");
        return 0.0;
    }
    float sum = 0.0;
    int i;
    for (i = 0; i < num_students; i++) {
        sum += students[i].score;
    }
    return sum / num_students;
}

int main() {
    int choice;
    while (1) {
        printf("\n1. Add student\n");
        printf("2. Delete student\n");
        printf("3. Query student\n");
        printf("4. Print all students\n");
        printf("5. Average score\n");
        printf("6. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                add_student();
                break;
            case 2:
                delete_student();
                break;
            case 3:
                query_student();
                break;
            case 4:
                print_all_students();
                break;
            case 5:
                printf("Average score: %6.2f\n", average_score());
                break;
            case 6:
                exit(0);
            default:
                printf("Error: invalid choice!\n");
                break;
        }
    }
}