如何在另一个类中创建结构指针？

Question

我有 3 个类：Book、Student、LibrarySystem，我需要 3 个链接列表来存储数据，第一个链接列表称为节点，存储学生，第二个链接列表称为 studenBookNode，存储特定学生保留的书籍，我的第三个链接列表是 allBooksNode它存储创建的书籍对象 下面是我的实现：

class Book {
public:
    Book();
    Book(int id, string title, int year);
    ~Book();
    //some getter and setter functions
private:
    int bookId;
    string bookName;
    int bookYear;
    bool status;
};

class Student {
public:
    Student();
    Student(int id, string name);
    ~Student();
    Student(const Student& rightVal);
    //Student& operator=(const Student& rightVal);
    int getId();
    void setId(int id);
    string getName();
    void setName(string name);
    //studentBookNode methods
    bool isEmpty() const;
    int getLength() const;
    bool removeNode(int index);
    int findIndex(int studentId);
    struct studentBookNode {
        Book item;
        studentBookNode* next;
    };
    studentBookNode* stuhead;
    int studentBooks;
    studentBookNode* findPointer(int index) const;

private:
    int studentId;
    string studentName;
};

class LibrarySystem {
public:
    LibrarySystem();
    ~LibrarySystem();
    void addStudent(const int studentId, const string studentName);
    void addBook(const int bookId, const string bookName, const int bookYear);

    void deleteBook(const int bookId);
    void deleteStudent(const int studentId);
    void checkoutBook(const int bookId, const int studentId);
    void returnBook(const int bookId);
    void showAllBooks() const;
    void showBook(const int bookId) const;
    void showStudent(const int studentId) const;

    bool isEmpty() const;
    bool isBooksEmpty() const;
    bool removeNode(int index);
    bool removeBookNode(int index);

    int findBookIndex(int bookId);
    int findIndex(int studentId);
    int getLengthBooks() const;
    int getLength() const;

private:
    struct Node {
        Student item;
        Node* next;
    };
    Node* head;
    int Size;
    Node* findPointer(int index) const;
    struct allBooksNode {
        Book item;
        allBooksNode* next;
    };
    allBooksNode* bookHead;
    int bookSize;
    allBooksNode* findBookPointer(int index) const;
};

我在 LibrarySystem 中有一个 checkOutBook 方法，我需要在该方法中访问 studentBookNode，首先我检查 studentId 和 bookId 的可用性，然后如果它们可用，我需要将这本书添加到特定的学生 studentBookNode 但我不能由于范围而访问它我该如何解决这个问题，下面是我的实现：

void LibrarySystem::checkoutBook(const int bookId, const int studentId)
{
    bool bookExist = false;
    bool studentExist = false;
    Node* cur = head;
    int stuIndex;
    int bookIndex;
    allBooksNode* curBook = bookHead;
    for (int i = 1; i <= getLengthBooks(); i++) {
        if (curBook->item.getBookId() == bookId) {
            bookExist = true;
            bookIndex = i;
        }
        curBook = curBook->next;
    }
    if (bookExist) {
        for (int i = 1; i <= getLength(); i++) {
            if (cur->item.getId() == studentId) {
                studentExist = true;
                stuIndex = i;
            }
            cur = cur->next;
        }
    }
    else {
        cout << "Book :" << bookId << " does not exist for checkout" << endl;
    }
    if (bookExist == true && studentExist == true) {
        Node* stuTemp = findPointer(stuIndex);
        allBooksNode* bookTemp = findBookPointer(bookIndex);

        if (stuTemp->item.getLength() == 0) {
            //problem is here i cant create studentBookNode* here
          studentBookNode* temp = new studentBookNode();
        }
    }
    else {
        cout << "Student: " << studentId << " does not exist for checkout" << endl;
    }
}

我试图创建一个指向 studentBookNode 的指针：

studentBookNode* temp = new studentBookNode();

错误信息是

studentBookNode was not declared in this scope

Answer 1

studentBookNode 是 Student 类的成员。除非您正在编写类 Student 的成员，否则此名称只能作为 Student::studentBookNode 访问。