用链表实现图书馆程序的代码，功能包括向图书馆添加书、借出书、还书、显示图书馆当前状态和退出程序

下面是用链表实现图书馆程序的代码示例：

class Book:
    def __init__(self, title, author, isbn, available=True):
        self.title = title
        self.author = author
        self.isbn = isbn
        self.available = available

class Library:
    def __init__(self):
        self.books = []

    def add_book(self, title, author, isbn):
        # 向图书馆添加书
        book = Book(title, author, isbn)
        self.books.append(book)
    
    def borrow_book(self, isbn):
        # 借出书
        for book in self.books:
            if book.isbn == isbn and book.available:
                book.available = False
                return True
        return False
    
    def return_book(self, isbn):
        # 还书
        for book in self.books:
            if book.isbn == isbn and not book.available:
                book.available = True
                return True
        return False
    
    def display_books(self):
        # 显示图书馆当前状态
        for book in self.books:
            print(f'Title: {book.title}, Author: {book.author}, ISBN: {book.isbn}, Available: {book.available}')
    
    def exit(self):
        # 退出程序
        print('Thank you for using the library system. Bye!')
        exit()

# 创建图书馆对象
library = Library()

# 向图书馆添加书
library.add_book('Book A', 'Author A', '12345')
library.add_book('Book B', 'Author B', '23456')
library.add_book('Book C', 'Author C', '34567')

# 借出书
library.borrow_book('12345')

# 显示图书馆当前状态
library.display_books()

# 还书
library.return_book('12345')

# 显示图书馆当前状态
library.display_books()

# 退出程序
library.exit()

这个代码示例实现了一个简单的图书馆程序，可以通过链表实现对图书的增删改查操作。其中，`Book` 类表示图书，