给定某学生学号修改该学生班级信息的代码

以下是修改学生班级信息的代码示例：

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

#define MAX_STUDENT_NUM 100
#define MAX_CLASS_NAME_LEN 20

typedef struct {
    char id[10];
    char name[20];
    char class_name[MAX_CLASS_NAME_LEN];
} Student;

int main() {
    Student students[MAX_STUDENT_NUM];
    int student_num = ;
    char target_id[10];
    char new_class_name[MAX_CLASS_NAME_LEN];

    // 读取学生信息
    FILE *fp = fopen("students.txt", "r");
    if (fp == NULL) {
        printf("无法打开文件\n");
        return 1;
    }
    while (fscanf(fp, "%s %s %s", students[student_num].id, students[student_num].name, students[student_num].class_name) != EOF) {
        student_num++;
    }
    fclose(fp);

    // 输入要修改的学生学号和新班级名称
    printf("请输入要修改的学生学号：");
    scanf("%s", target_id);
    printf("请输入新的班级名称：");
    scanf("%s", new_class_name);

    // 查找要修改的学生并修改班级名称
    int found = ;
    for (int i = ; i < student_num; i++) {
        if (strcmp(students[i].id, target_id) == ) {
            strcpy(students[i].class_name, new_class_name);
            found = 1;
            break;
        }
    }

    // 输出修改结果
    if (found) {
        fp = fopen("students.txt", "w");
        if (fp == NULL) {
            printf("无法打开文件\n");
            return 1;
        }
        for (int i = ; i < student_num; i++) {
            fprintf(fp, "%s %s %s\n", students[i].id, students[i].name, students[i].class_name);
        }
        fclose(fp);
        printf("修改成功！\n");
    } else {
        printf("未找到该学生！\n");
    }

    return ;
}