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

这里提供一个主测试文件的示例代码，其他文件的具体实现需要根据题目要求自行编写。

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

using namespace std;

int main() {
    Library library;
    int choice;
    do {
        cout << "1. Add book" << endl;
        cout << "2. Add patron" << endl;
        cout << "3. Check out book" << endl;
        cout << "4. List patrons with fees" << endl;
        cout << "5. Quit" << endl;
        cout << "Enter your choice: ";
        cin >> choice;
        switch(choice) {
            case 1: {
                string title, author;
                cout << "Enter book title: ";
                cin >> title;
                cout << "Enter book author: ";
                cin >> author;
                Book book(title, author);
                library.addBook(book);
                cout << "Book added successfully!" << endl;
                break;
            }
            case 2: {
                string name;
                int id;
                cout << "Enter patron name: ";
                cin >> name;
                cout << "Enter patron ID: ";
                cin >> id;
                Patron patron(name, id);
                library.addPatron(patron);
                cout << "Patron added successfully!" << endl;
                break;
            }
            case 3: {
                int bookId, patronId;
                cout << "Enter book ID: ";
                cin >> bookId;
                cout << "Enter patron ID: ";
                cin >> patronId;
                Book book = library.getBook(bookId);
                Patron patron = library.getPatron(patronId);
                if (book.getTitle() == "" || patron.getName() == "") {
                    cout << "Error: Book or patron not found!" << endl;
                } else if (patron.getFees() > 0) {
                    cout << "Error: Patron has unpaid fees!" << endl;
                } else {
                    Date date;
                    Transaction transaction(book, patron, date);
                    library.addTransaction(transaction);
                    cout << "Book checked out successfully!" << endl;
                }
                break;
            }
            case 4: {
                vector<string> patronsWithFees = library.getPatronsWithFees();
                if (patronsWithFees.size() == 0) {
                    cout << "No patrons with unpaid fees." << endl;
                } else {
                    cout << "Patrons with unpaid fees: ";
                    for (string patronName : patronsWithFees) {
                        cout << patronName << ", ";
                    }
                    cout << endl;
                }
                break;
            }
            case 5: {
                cout << "Goodbye!" << endl;
                break;
            }
            default: {
                cout << "Invalid choice. Please try again." << endl;
                break;
            }
        }
    } while (choice != 5);
    return 0;
}