Group
Working with Relational Databases in C#
Objective
1. When the program starts, it checks if a data file exists. If it doesn't, a new file will be created.
2. The user is prompted to enter the book's title, author, and publication year.
3. The user can then view the list of all entered books.
4. The program ensures that the data is saved and can be accessed after restarting the program.
5. Handle potential input errors (such as invalid data formats).
Create a program that allows the user to enter information about books and browse the existing data. It should handle the case where the data file does not exist when the program starts.
Example C# Exercise
Show C# Code
using System;
using System.Collections.Generic;
using System.IO;
// Book class to store information about each book
public class Book
{
public string Title { get; set; }
public string Author { get; set; }
public int Year { get; set; }
// Constructor to initialize a new book
public Book(string title, string author, int year)
{
Title = title;
Author = author;
Year = year;
}
// Method to display book details
public override string ToString()
{
return $"{Title} by {Author} ({Year})";
}
}
class Program
{
// File path for storing book data
static string filePath = "books.txt";
// List to store books
static List books = new List();
// Main method to run the program
static void Main(string[] args)
{
// Check if the file exists. If not, create a new one.
if (File.Exists(filePath))
{
// Load existing book data from the file
LoadBooks();
}
else
{
// Create a new file if it does not exist
File.Create(filePath).Dispose();
}
// Allow user to input new book data
while (true)
{
Console.WriteLine("Enter book title (or type 'exit' to quit):");
string title = Console.ReadLine();
if (title.ToLower() == "exit") break;
Console.WriteLine("Enter book author:");
string author = Console.ReadLine();
Console.WriteLine("Enter publication year:");
int year;
while (!int.TryParse(Console.ReadLine(), out year))
{
Console.WriteLine("Invalid input. Please enter a valid year:");
}
// Create a new Book object and add it to the list
Book newBook = new Book(title, author, year);
books.Add(newBook);
// Save the book to the file
SaveBooks();
}
// Display all entered books
Console.WriteLine("\nBooks in the system:");
foreach (var book in books)
{
Console.WriteLine(book);
}
}
// Method to load books from the file
static void LoadBooks()
{
// Read each line from the file and convert it to a Book object
string[] lines = File.ReadAllLines(filePath);
foreach (string line in lines)
{
var parts = line.Split(',');
string title = parts[0].Trim();
string author = parts[1].Trim();
int year = int.Parse(parts[2].Trim());
books.Add(new Book(title, author, year));
}
}
// Method to save books to the file
static void SaveBooks()
{
// Clear the file and write the updated list of books
File.WriteAllLines(filePath, books.ConvertAll(book => $"{book.Title}, {book.Author}, {book.Year}"));
}
}
Output
Enter book title (or type 'exit' to quit):
The Great Gatsby
Enter book author:
F. Scott Fitzgerald
Enter publication year:
1925
Enter book title (or type 'exit' to quit):
Moby Dick
Enter book author:
Herman Melville
Enter publication year:
1851
Enter book title (or type 'exit' to quit):
exit
Books in the system:
The Great Gatsby by F. Scott Fitzgerald (1925)
Moby Dick by Herman Melville (1851)