创建一个 Library类，包含一个 Book向量和一个Patron向量。定义一个名为Transaction 的 struet，包含一个Book对象、一个Patron对象和一个本章中定义的Date对象，表示借阅记录。在 Library 类中定义一个Transaction向量。定义向图书馆添加图书、添加读者以及借出书籍的函数。当一个读者借出一本书时,保证Library对象中有此读者和这本书的记录,否则报告错误。然后检查读者是否欠费，如果欠费就报告一个错误,否则创建一个Transaction对象，将其放人Transaction向量中。定义一个返回包含所有欠费读者姓名的向量的函数。该软件是多文件程序，按文件给出代码，在主测试文件中设置菜单，由用户手动录入图书信息，用C++设计实现，只需要写出主测试文件

以下是主测试文件的代码，实现了添加图书、添加读者、借出书籍以及查看欠费读者的功能：

#include <iostream>
#include <vector>
#include "Library.h"

using namespace std;

// 函数声明
void printMenu();
void addBookToLibrary(Library& lib);
void addPatronToLibrary(Library& lib);
void checkoutBook(Library& lib);
void viewFines(Library& lib);

int main() {
    Library lib;  // 创建图书馆对象

    int choice;
    do {
        printMenu();
        cin >> choice;

        switch (choice) {
            case 1:
                addBookToLibrary(lib);
                break;
            case 2:
                addPatronToLibrary(lib);
                break;
            case 3:
                checkoutBook(lib);
                break;
            case 4:
                viewFines(lib);
                break;
            case 5:
                cout << "Goodbye!" << endl;
                break;
            default:
                cout << "Invalid choice. Please try again." << endl;
                break;
        }

        cout << endl;
    } while (choice != 5);

    return 0;
}

// 打印菜单
void printMenu() {
    cout << "Welcome to the Library!" << endl;
    cout << "1. Add a book to the library" << endl;
    cout << "2. Add a patron to the library" << endl;
    cout << "3. Checkout a book" << endl;
    cout << "4. View fines" << endl;
    cout << "5. Quit" << endl;
    cout << "Enter your choice: ";
}

// 向图书馆添加图书
void addBookToLibrary(Library& lib) {
    string title, author;
    int year;

    cout << "Enter the book title: ";
    cin.ignore();
    getline(cin, title);

    cout << "Enter the book author: ";
    getline(cin, author);

    cout << "Enter the year the book was published: ";
    cin >> year;

    Book book(title, author, year);
    lib.addBook(book);

    cout << "Book added successfully!" << endl;
}

// 向图书馆添加读者
void addPatronToLibrary(Library& lib) {
    string name;
    int id;

    cout << "Enter the patron name: ";
    cin.ignore();
    getline(cin, name);

    cout << "Enter the patron ID: ";
    cin >> id;

    Patron patron(name, id);
    lib.addPatron(patron);

    cout << "Patron added successfully!" << endl;
}

// 借出书籍
void checkoutBook(Library& lib) {
    int bookId, patronId;

    cout << "Enter the book ID: ";
    cin >> bookId;

    cout << "Enter the patron ID: ";
    cin >> patronId;

    Book book = lib.getBook(bookId);
    Patron patron = lib.getPatron(patronId);

    if (book.getId() == -1) {
        cout << "Book not found. Please try again." << endl;
        return;
    }

    if (patron.getId() == -1) {
        cout << "Patron not found. Please try again." << endl;
        return;
    }

    if (lib.isPatronOwesFines(patron)) {
        cout << "Patron owes fines and cannot checkout books." << endl;
        return;
    }

    if (!lib.isBookAvailable(book)) {
        cout << "Book is not available for checkout." << endl;
        return;
    }

    Transaction transaction(book, patron, Date());
    lib.addTransaction(transaction);

    cout << "Book checked out successfully!" << endl;
}

// 查看欠费读者
void viewFines(Library& lib) {
    vector<string> patrons = lib.getPatronsOwingFines();

    if (patrons.size() == 0) {
        cout << "No patrons owe fines." << endl;
        return;
    }

    cout << "Patrons owing fines:" << endl;
    for (int i = 0; i < patrons.size(); i++) {
        cout << "- " << patrons[i] << endl;
    }
}

其中，Library类的头文件定义如下：

#ifndef LIBRARY_H
#define LIBRARY_H

#include <vector>
#include "Book.h"
#include "Patron.h"
#include "Transaction.h"

class Library {
public:
    void addBook(const Book& book);
    void addPatron(const Patron& patron);
    void addTransaction(const Transaction& transaction);
    bool isBookAvailable(const Book& book) const;
    bool isPatronOwesFines(const Patron& patron) const;
    Book getBook(int id) const;
    Patron getPatron(int id) const;
    std::vector<std::string> getPatronsOwingFines() const;

private:
    std::vector<Book> books;
    std::vector<Patron> patrons;
    std::vector<Transaction> transactions;
    static const double DAILY_FINE = 0.1;
};

#endif

其中，Book、Patron和Transaction类的定义分别如下：

#ifndef BOOK_H
#define BOOK_H

#include <string>

class Book {
public:
    Book(std::string title, std::string author, int year);
    int getId() const;
    std::string getTitle() const;
    std::string getAuthor() const;
    int getYear() const;
    bool isCheckedOut() const;
    void checkOut();
    void checkIn();

private:
    static int nextId;
    int id;
    std::string title;
    std::string author;
    int year;
    bool checkedOut;
};

#endif

#ifndef PATRON_H
#define PATRON_H

#include <string>

class Patron {
public:
    Patron(std::string name, int id);
    int getId() const;
    std::string getName() const;
    double getFines() const;
    void addFine(double fine);
    void payFines();

private:
    int id;
    std::string name;
    double fines;
};

#endif

#ifndef TRANSACTION_H
#define TRANSACTION_H

#include "Book.h"
#include "Patron.h"
#include "Date.h"

class Transaction {
public:
    Transaction(Book book, Patron patron, Date date);
    Book getBook() const;
    Patron getPatron() const;
    Date getDate() const;

private:
    Book book;
    Patron patron;
    Date date;
};

#endif

其他类的实现可根据需要自行编写。