200行代码的python程序

好的，这里是一个200行左右的Python程序，它是一个简单的图书管理系统，包括添加图书、借阅图书、归还图书、查询图书等功能：

class Book:
    def __init__(self, title, author, isbn, num_copies):
        self.title = title
        self.author = author
        self.isbn = isbn
        self.num_copies = num_copies
        self.num_available = num_copies

    def __str__(self):
        return f"{self.title} by {self.author}"

    def display(self):
        print(f"Title: {self.title}")
        print(f"Author: {self.author}")
        print(f"ISBN: {self.isbn}")
        print(f"Number of Copies: {self.num_copies}")
        print(f"Number of Available Copies: {self.num_available}")

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

    def add_book(self, book):
        self.books.append(book)

    def remove_book(self, book):
        self.books.remove(book)

    def find_book_by_title(self, title):
        for book in self.books:
            if book.title == title:
                return book
        return None

    def find_book_by_author(self, author):
        matching_books = []
        for book in self.books:
            if book.author == author:
                matching_books.append(book)
        return matching_books

    def display_books(self):
        for book in self.books:
            book.display()

class Borrower:
    def __init__(self, name):
        self.name = name
        self.borrowed_books = []

    def borrow_book(self, book):
        if book.num_available == 0:
            print("Sorry, this book is not available for borrowing.")
        else:
            book.num_available -= 1
            self.borrowed_books.append(book)

    def return_book(self, book):
        if book in self.borrowed_books:
            book.num_available += 1
            self.borrowed_books.remove(book)
        else:
            print("You did not borrow this book from the library.")

    def display_borrowed_books(self):
        if len(self.borrowed_books) == 0:
            print("You have not borrowed any books from the library.")
        else:
            print("Your borrowed books:")
            for book in self.borrowed_books:
                print(book)

def main():
    library = Library()
    book1 = Book("The Great Gatsby", "F. Scott Fitzgerald", "978-0141182636", 5)
    book2 = Book("To Kill a Mockingbird", "Harper Lee", "978-0446310789", 3)
    book3 = Book("1984", "George Orwell", "978-0451524935", 2)
    library.add_book(book1)
    library.add_book(book2)
    library.add_book(book3)

    borrower1 = Borrower("Alice")
    borrower2 = Borrower("Bob")

    while True:
        print()
        print("Welcome to the Library Management System!")
        print("1. Add a book")
        print("2. Remove a book")
        print("3. Find a book by title")
        print("4. Find books by author")
        print("5. Display all books")
        print("6. Borrow a book")
        print("7. Return a book")
        print("8. Display borrowed books")
        print("9. Quit")

        try:
            choice = int(input("Please enter your choice: "))
        except ValueError:
            print("Invalid choice. Please enter a number.")
            continue

        if choice == 1:
            title = input("Please enter the book title: ")
            author = input("Please enter the book author: ")
            isbn = input("Please enter the book ISBN: ")
            num_copies = int(input("Please enter the number of copies: "))
            book = Book(title, author, isbn, num_copies)
            library.add_book(book)
            print("Book added successfully.")

        elif choice == 2:
            title = input("Please enter the title of the book you want to remove: ")
            book = library.find_book_by_title(title)
            if book:
                library.remove_book(book)
                print("Book removed successfully.")
            else:
                print("Book not found.")

        elif choice == 3:
            title = input("Please enter the book title: ")
            book = library.find_book_by_title(title)
            if book:
                book.display()
            else:
                print("Book not found.")

        elif choice == 4:
            author = input("Please enter the author name: ")
            matching_books = library.find_book_by_author(author)
            if len(matching_books) == 0:
                print("No matching books found.")
            else:
                print("Matching books:")
                for book in matching_books:
                    book.display()

        elif choice == 5:
            library.display_books()

        elif choice == 6:
            title = input("Please enter the title of the book you want to borrow: ")
            book = library.find_book_by_title(title)
            if book:
                borrower = input("Please enter your name: ")
                if borrower == borrower1.name:
                    borrower1.borrow_book(book)
                elif borrower == borrower2.name:
                    borrower2.borrow_book(book)
                else:
                    print("Borrower not found.")
            else:
                print("Book not found.")

        elif choice == 7:
            title = input("Please enter the title of the book you want to return: ")
            book = library.find_book_by_title(title)
            if book:
                borrower = input("Please enter your name: ")
                if borrower == borrower1.name:
                    borrower1.return_book(book)
                elif borrower == borrower2.name:
                    borrower2.return_book(book)
                else:
                    print("Borrower not found.")
            else:
                print("Book not found.")

        elif choice == 8:
            borrower = input("Please enter your name: ")
            if borrower == borrower1.name:
                borrower1.display_borrowed_books()
            elif borrower == borrower2.name:
                borrower2.display_borrowed_books()
            else:
                print("Borrower not found.")

        elif choice == 9:
            print("Goodbye!")
            break

        else:
            print("Invalid choice. Please enter a number between 1 and 9.")

if __name__ == '__main__':
    main()

这个程序使用了面向对象的编程风格，其中定义了三个类：Book、Library和Borrower。Book类表示一本书，包括书名、作者、ISBN和库存数量等属性，以及展示书籍信息的方法。Library类表示图书馆，包括添加图书、删除图书、查找图书等方法。Borrower类表示借阅者，包括借阅图书、归还图书、展示已借阅图书等方法。

在主函数中，用户可以选择不同的操作，例如添加图书、借阅图书、归还图书、查询图书等。每个操作都会调用相应的方法来完成相应的任务。程序也包含了一些错误处理，例如用户输入非法的选项时会提示用户重新输入。