C-指针内部结构错误(?)

Question

我正在尝试在C中创建一个将读取文件的小程序，它将显示，添加和删除该文件的数据。

因此，基本上，我有一个预定义的文件（当然应该与任何文件一起使用）：https：//hastebin.com/oficewuveh.pas

当我尝试使用getStudentById（）方法时，它可以正常工作，直到将另一个用户添加到文件中为止。我将代码删除了，但它仍然很大，很抱歉。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Lesson {
    char *name;
    int semester;
    float grade;
} Lesson;
typedef struct Student {
    char *name;
    char *surname;
    int id;
    int numberOfLessons;
    Lesson *lesson;
} Student;
typedef struct Database {
    int numberOfStudents;
    Student *student;
} StudentDB;
static int maxNameSize = 100;
static int autoclear = 0;
static int enableTimeout = 0;

void main() {
    system("color 02");
    system("@echo off");
    FILE *studentFile;
    StudentDB database;
    //add = { 0, NULL} ?
    studentFile = fopen("students.txt", "r+w");
    int numberOfStudents;
    //Set the number of students
    fscanf(studentFile, "%d", &database.numberOfStudents);
    //Prints the number of students
    printf("Number of students: %dn", database.numberOfStudents);
    //Set the memory allocation
    database.student = malloc(database.numberOfStudents * sizeof(Student));
    if(!database.student) {
        printf("The memory allocation has failed. Exiting the program!");
        exit(0);
    }   
    //Read the students
    readData(studentFile, &database);   
    run(studentFile, &database);
}
Lesson addLesson() {
    Lesson lesson;
    lesson.name = malloc(maxNameSize * sizeof(char));
    if(!lesson.name) { printf("Memory Allocation has failed. Exiting the program!"); exit(0); }
    printf("tName of the lesson: ");
    scanf("%s", &lesson.name);
    printf("tSemester: ");
    scanf("%d", &lesson.semester);
    printf("tGrade: ");
    scanf("%f", &lesson.grade);
    return lesson;
}
void addStudent(StudentDB *database) {
    database->numberOfStudents = database->numberOfStudents + 1;
    printf("nAdded +1 to number of students, now is %dn", database->numberOfStudents);
    int numOfStudents = database->numberOfStudents;
    database->student = realloc(database->student, (numOfStudents + 1) * sizeof(Student));
    Student student;
    student.name = malloc(maxNameSize * sizeof(char));
    student.surname = malloc(maxNameSize * sizeof(char));
    if(!student.name) { printf("Memory Allocation has failed. Exiting the program!"); exit(0); }
    if(!student.surname) { printf("Memory Allocation has failed. Exiting the program!"); exit(0); }
    printf("tAdding a new Studentnn");
    printf("Name of the student: ");
    scanf("%s", student.name);
    printf("Surname of the student: ");
    scanf("%s", student.surname);
    printf("ID of the student: ");
    scanf("%s", &student.id);
    int numOfLessons;
    printf("How many classes does that student take: ");
    scanf("%d", &numOfLessons);
    int i;
    //Lesson lesson[numOfLessons];
    for(i = 0; i < numOfLessons; i++) {
        printf("Adding lesson %dn", i);
        student.lesson[i] = addLesson();
    }
    printf("%d", numOfStudents);
//  displayStudent(student);
    database->student[numOfStudents - 1] = student;
}
void displayStudent(Student student) {
    printf("Displaying all the info for the student with ID: %dn", student.id);
    printf("tID: tt %d  n", student.id);
    printf("tFull Name:t %s %s n", student.name, student.surname);
    printf("tLessons :t %d n", student.numberOfLessons);
    printf("t  n");
    printf("ttDisplaying Lessonsn");
    int i;
    for(i = 0; i < student.numberOfLessons; i++) {
        displayLesson(student.lesson[i]);
    }
    system("PAUSE");
}
Student getStudentByID(StudentDB *database) {
    printf("Give us the ID of the student: ");
    int id;
    scanf("%d", &id);
    printf("Done saving the id: %dn", id);
    int i;
    for(i = 0; i < database->numberOfStudents; i++) {
        printf("Comparing %d and %dn", id, database->student[i].id);
        if(id == database->student[i].id) {
            printf("ID found, returning studentn");
            return database->student[i];
        }
    }
    Student student;
    student.name = malloc(4 * sizeof(char));
    student.name = "NULL";
    printf("ID not found, returning NULLn");
    return student;
}
//Successfully gets the lessons. Everything is fine here
Lesson getNextLesson(FILE *studentFile) {
    //Code to read the lesson..
    return lesson;
}
//Successfully gets a student and the lessons. Everything is fine here
Student getNextStudent(FILE *studentFile) {
    //Code to read the student..
    return student;
}
void run(FILE *studentFile, StudentDB *database) {
    int answer;
    //Menu and more code...
    addStudent(database);
}
void readData(FILE *studentFile, StudentDB *db) {
    int i;
    printf("Running the loopn");
    for(i = 0; i < db->numberOfStudents; i++) {
        printf("=====================nntStudent #%dn", i);
        db->student[i] = getNextStudent(studentFile);
        printf("ntCompletednn=====================n");
    }
}
void swapStudents(Student *student1, Student *student2) {
    Student temp;
    temp = *student1;
    *student1 = *student2;
    *student2 = temp;
}

这可能是指针某个地方的错误，通常对指针和C一般。

。

所以，当我添加一个新学生时，它会返回以下内容：https：//hastebin.com/uwequefiket.coffeescript（查看文件末尾）

我一直在试图弄清楚我做错了什么，但是我无法弄清楚，所以我来了。如果有人有兴趣，这是完整的代码：https：//hastebin.com/yolagekire.cpp

事先感谢您的任何帮助！

Answer 1

printf("ID of the student: ");
scanf("%s", &student.id);

id是一个数字，但是在这里，您将其读为字符串。将代码更改为

printf("ID of the student: ");
scanf("%d", &student.id);