修改代码错误int read_student_info(student students[]) { int i = 0; FILE *fp; fp = fopen("d:/学生系统/student.txt", "r"); if (fp == NULL) { printf("打开文件失败！\n"); return 0; } while (fscanf(fp, "%s %s %s %d/%d/%d %d %d %d", &students[num_students].num, students[num_students].name, students[num_students].sex, &students[num_students].year, &students[num_students].month, &students[num_students].day, &students[num_students].score[1], &students[num_students].score[2], &students[num_students].score[3]) != EOF) { students[num_students].total = students[num_students].score[1] + students[num_students].score[2] + students[num_students].score[3]; students[num_students].average = students[num_students].total / 3; num_students++; if (num_students>=MAX_STUDENTS) { printf("已有太多学生信息!\n"); break; } } fclose(fp); return num_students; }

在代码中，缺少定义变量num_students和MAX_STUDENTS，需要加上如下定义：

#define MAX_STUDENTS 100 // 假设最多有100个学生信息

int read_student_info(student students[]) {
    int i = 0;
    int num_students = 0; // 定义记录学生个数的变量
    FILE *fp;
    fp = fopen("d:/学生系统/student.txt", "r");
    if (fp == NULL) {
        printf("打开文件失败！\n");
        return 0;
    }
    while (fscanf(fp, "%s %s %s %d/%d/%d %d %d %d",
                  &students[num_students].num,
                  students[num_students].name,
                  students[num_students].sex,
                  &students[num_students].year,
                  &students[num_students].month,
                  &students[num_students].day,
                  &students[num_students].score[1],
                  &students[num_students].score[2],
                  &students[num_students].score[3]) != EOF) {
        students[num_students].total = students[num_students].score[1] + students[num_students].score[2] + students[num_students].score[3];
        students[num_students].average = students[num_students].total / 3;
        num_students++;
        if (num_students >= MAX_STUDENTS) {
            printf("已有太多学生信息!\n");
            break;
        }
    }
    fclose(fp);
    return num_students;
}

这样修改后，代码就能正确地读取学生信息并返回学生个数了。