class Customer { private string name; private int id;

public string Name { get { return name; } set { name = value; } } public int Id { get { return id; } } public Customer(string name, int id) { this.name = name; this.id = id; } public string ToString() { string p = string.Format("{0,-6} {1,-10}\n", id, name); return p; } }
}

class GeneralBook:Book { public override DateTime findDueDate() { System.DateTime td = System.DateTime.Now; System.DateTime fb = td.AddDays(7); return fb; } public GeneralBook(string title, string authors, int catalogNo) : base(title, authors, catalogNo) { } }

}

namespace ConsoleApplication1
{
interface IRenewable { bool Renew(); }
}
private Customer[] customerArray = new Customer[5]; private Book[] bookArray = new Book[5]; private int customerId = 0; private int catalogNo = 100; public bool AddNewCustomer(string customerName) { if (customerId < customerArray.Length) { customerArray[customerId] = new Customer(customerName, ++customerId); return true; }

else { return false; } } public bool AddNewBook(string bookTitle, string bookAuthor) { if (catalogNo - 100 < bookArray.Length) { bookArray[catalogNo - 100] = new GeneralBook(bookTitle, bookAuthor, ++catalogNo); return true; } else { return false; }

} public bool AddNewBook(string bTitle, string bAuthor, int edition) { if (catalogNo - 100 < bookArray.Length) { bookArray[catalogNo - 100] = new TextBook(bTitle, bAuthor, ++catalogNo,edition); return true; } else { return false; }

} public string ToString() { string p = "Customers:\n"; for (int i = 0; i < customerId; i++) { p += customerArray[i].ToString(); } p += "Books:\n"; for (int i = 0; i < catalogNo-100; i++) { p += bookArray[i].ToString(); } return p; } public bool IssueBook(int custId, int bookCatalogNum) { if (bookCatalogNum > catalogNo || custId > customerId) { return false; } return bookArray[bookCatalogNum - 101].CheckOut(customerArray[custId - 1]); } public bool ReturnBook(int bookCatalogNum) { if (bookCatalogNum > catalogNo) { return false; } return bookArray[bookCatalogNum - 101].CheckIn(); } public bool RenewBook(int catalogNum) { try { return ((TextBook)bookArray[catalogNum - 101]).Renew(); } catch { return false; } } }
}

namespace ConsoleApplication1
{
class TextBook : Book , IRenewable { int edition; //Override the findDueDate() method in the TextBook class so that it computes and //returns a date 30 days from the date of checkout. public override DateTime findDueDate() { System.DateTime td = System.DateTime.Now; System.DateTime fb = td.AddDays(30); return fb; } public override string ToString() { string p; p = base.ToString(); p += "Edition:" + edition.ToString() ; return p; } public bool Renew() { if (this.c != null) { DateTime rr = findDueDate(); DateTime nd = rr.AddDays (15); return true; } else { return false; } } public TextBook (string title, string authors, int catalogNo,int ed):base(title, authors,catalogNo) { this.edition=ed; } }
}