public void AddBook(Book aBook)
{
if (LookupBook(aBook.GetISBN()) != null)
{
Console.WriteLine($"ISBN {aBook.GetISBN()} er allerede i brug!");
}
else
{
books.Add(aBook);
Console.WriteLine($"Bogen {aBook.GetISBN()} er tilføjet!");
}
books.Add(aBook); // Add code that can add the given Book object to the list
}
public void AddBook(Book aBook)
{
books.Add(aBook.GetISBN(), aBook);
}