此题和接下来的几道题要求你设计并实现一个Book类,你可以设想这是图书馆软件系统的一部分。Book类应包含表示ISBN号、书名、作者和版权日期以及表示是否已经借出的成员。创建能返回这些成员的值的函数，以及借书和还书的函数。对于输人Book对象的数据进行简单的有效性检查，例如,只接受n-n-n-x形式的ISBN号，其中n是一个整数，x是一个数字或一个字母。 为Book类添加运算符。添加==运算符,用于检查两本书的 ISBN 号是否相等。定义!=运算符，比较ISBN号是否不等。定义<<，分行输出书名、作者和ISBN号。 为Book类创建一个名为Genre的枚举类型,用以区分书籍的类型:小说(fiction)、非小说类文学作品(nonfiction)、期刊(periodical)、传记(biography)、儿童读物(children)。为每本书赋予一个Genre值,适当修改Book的构造函数和成员函数。要在测试文件图书的录入操作由用户可以手动添加，多文件操作，按文件给出代码

好的，我可以帮你设计并实现一个Book类。以下是代码实现：

Book.h文件：

#ifndef BOOK_H
#define BOOK_H

#include <string>

enum Genre { FICTION, NONFICTION, PERIODICAL, BIOGRAPHY, CHILDREN };

class Book {
private:
    std::string isbn;
    std::string title;
    std::string author;
    std::string copyrightDate;
    bool isBorrowed;
    Genre genre;

public:
    Book(std::string isbn, std::string title, std::string author, std::string copyrightDate, 
         bool isBorrowed, Genre genre);
    std::string getIsbn() const;
    std::string getTitle() const;
    std::string getAuthor() const;
    std::string getCopyrightDate() const;
    bool getIsBorrowed() const;
    Genre getGenre() const;
    void setIsBorrowed(bool isBorrowed);
    void borrow();
    void returnBook();
    bool isValidISBN(std::string isbn);
};

bool operator==(const Book& b1, const Book& b2);
bool operator!=(const Book& b1, const Book& b2);
std::ostream& operator<<(std::ostream& os, const Book& b);

#endif

Book.cpp文件：

#include "Book.h"
#include <iostream>

Book::Book(std::string isbn, std::string title, std::string author, std::string copyrightDate,
           bool isBorrowed, Genre genre)
    : isbn(isbn), title(title), author(author), copyrightDate(copyrightDate),
      isBorrowed(isBorrowed), genre(genre) {}

std::string Book::getIsbn() const {
    return isbn;
}

std::string Book::getTitle() const {
    return title;
}

std::string Book::getAuthor() const {
    return author;
}

std::string Book::getCopyrightDate() const {
    return copyrightDate;
}

bool Book::getIsBorrowed() const {
    return isBorrowed;
}

Genre Book::getGenre() const {
    return genre;
}

void Book::setIsBorrowed(bool isBorrowed) {
    this->isBorrowed = isBorrowed;
}

void Book::borrow() {
    isBorrowed = true;
}

void Book::returnBook() {
    isBorrowed = false;
}

bool Book::isValidISBN(std::string isbn) {
    if (isbn.length() != 9)
        return false;

    for (int i = 0; i < 3; i++) {
        if (!isdigit(isbn[i]))
            return false;
    }

    if (isbn[3] != '-')
        return false;

    for (int i = 4; i < 7; i++) {
        if (!isdigit(isbn[i]))
            return false;
    }

    if (isbn[7] != '-')
        return false;

    if (!isalnum(isbn[8]))
        return false;

    return true;
}

bool operator==(const Book& b1, const Book& b2) {
    return b1.getIsbn() == b2.getIsbn();
}

bool operator!=(const Book& b1, const Book& b2) {
    return b1.getIsbn() != b2.getIsbn();
}

std::ostream& operator<<(std::ostream& os, const Book& b) {
    os << "Title: " << b.getTitle() << std::endl;
    os << "Author: " << b.getAuthor() << std::endl;
    os << "ISBN: " << b.getIsbn() << std::endl;
    return os;
}

main.cpp文件：

#include "Book.h"
#include <iostream>
#include <fstream>
#include <vector>

void addBook(std::vector<Book>& books) {
    std::string isbn, title, author, copyright;
    int genre;

    std::cout << "Enter the ISBN (format n-n-n-x): ";
    std::cin >> isbn;
    while (!Book::isValidISBN(isbn)) {
        std::cout << "Invalid ISBN format. Please try again." << std::endl;
        std::cout << "Enter the ISBN (format n-n-n-x): ";
        std::cin >> isbn;
    }

    std::cout << "Enter the title: ";
    std::cin >> title;

    std::cout << "Enter the author: ";
    std::cin >> author;

    std::cout << "Enter the copyright date: ";
    std::cin >> copyright;

    std::cout << "Enter the genre (0 for fiction, 1 for nonfiction, 2 for periodical, 3 for biography, 4 for children): ";
    std::cin >> genre;

    books.push_back(Book(isbn, title, author, copyright, false, static_cast<Genre>(genre)));
}

void saveBooks(std::vector<Book>& books) {
    std::ofstream fout("books.txt");

    for (const auto& b : books) {
        fout << b.getIsbn() << " " << b.getTitle() << " " << b.getAuthor() << " " << b.getCopyrightDate()
             << " " << b.getIsBorrowed() << " " << b.getGenre() << std::endl;
    }

    fout.close();
}

void loadBooks(std::vector<Book>& books) {
    std::ifstream fin("books.txt");

    if (fin) {
        std::string line;

        while (getline(fin, line)) {
            std::istringstream iss(line);
            std::string isbn, title, author, copyright;
            bool isBorrowed;
            int genre;

            iss >> isbn >> title >> author >> copyright >> isBorrowed >> genre;

            books.push_back(Book(isbn, title, author, copyright, isBorrowed, static_cast<Genre>(genre)));
        }
    }

    fin.close();
}

int main() {
    std::vector<Book> books;
    loadBooks(books);

    int choice;

    do {
        std::cout << "1. Add book" << std::endl;
        std::cout << "2. Borrow book" << std::endl;
        std::cout << "3. Return book" << std::endl;
        std::cout << "4. List all books" << std::endl;
        std::cout << "5. Save and exit" << std::endl;
        std::cout << "Enter your choice: ";
        std::cin >> choice;

        switch (choice) {
        case 1:
            addBook(books);
            break;
        case 2: {
            std::string isbn;
            std::cout << "Enter the ISBN of the book to borrow: ";
            std::cin >> isbn;

            auto it = std::find_if(books.begin(), books.end(), [isbn](const Book& b) { return b.getIsbn() == isbn; });

            if (it != books.end()) {
                if (it->getIsBorrowed()) {
                    std::cout << "This book is already borrowed." << std::endl;
                } else {
                    it->borrow();
                    std::cout << "Book borrowed successfully." << std::endl;
                }
            } else {
                std::cout << "Book not found." << std::endl;
            }

            break;
        }
        case 3: {
            std::string isbn;
            std::cout << "Enter the ISBN of the book to return: ";
            std::cin >> isbn;

            auto it = std::find_if(books.begin(), books.end(), [isbn](const Book& b) { return b.getIsbn() == isbn; });

            if (it != books.end()) {
                if (!it->getIsBorrowed()) {
                    std::cout << "This book is not borrowed." << std::endl;
                } else {
                    it->returnBook();
                    std::cout << "Book returned successfully." << std::endl;
                }
            } else {
                std::cout << "Book not found." << std::endl;
            }

            break;
        }
        case 4:
            for (const auto& b : books) {
                std::cout << b;
            }
            break;
        case 5:
            saveBooks(books);
            std::cout << "Exiting program." << std::endl;
            break;
        default:
            std::cout << "Invalid choice. Please try again." << std::endl;
            break;
        }

        std::cout << std::endl;

    } while (choice != 5);

    return 0;
}

books.txt文件：

123-456-7A The Great Gatsby F. Scott Fitzgerald 1925 0 0
456-789-0B To Kill a Mockingbird Harper Lee 1960 0 0
789-012-3C The Catcher in the Rye J.D. Salinger 1951 1 0

注意：以上代码只是一个简单的示例，实际应用中还需要更完善的错误处理和其他功能。