question 2

using System;
using System.Collections;

namespace ConsoleApplication2
{
    class Program
    {
        static Hashtable BorrowedList = new Hashtable();
        static void Main(string[] args)
        {
            string[] Books = new string[] { "Hunger games", "The Vinci Code", "The Secret of the Nagas", "The Immortals of Meluha", "Angles And Demons", "Two States", "Half Life", "Harry Potter and the Philosopher's Stone" };
            for (int i = 0; i < Books.Length; i++)
            {
                Console.WriteLine((i + 1) + "." + Books[i]);
            }
            while (true)
            {
                Console.WriteLine("enter 1 if you want to Borrow a Book \nEnter 2 if you want to return a book \n Enter 3 if you want to check Borrwed List");
                int a = int.Parse(Console.ReadLine());
                if (a == 1)
                {
                    Console.WriteLine("Write name of Book you want to borrow");
                    string BorrowBook = Console.ReadLine();
                    Console.WriteLine("enter Your Name");
                    string Name = Console.ReadLine();
                    if (BorrowedList.ContainsValue(Name))
                    {
                        if (BorrowedList.ContainsKey(BorrowBook))
                            throw new ApplicationException("You already Have Borrowed this Book");
                    }
                    Borrow(BorrowBook, Name);
                }
                else if (a == 2)
                {
                    Console.WriteLine("Write name of Book you want to return");
                    string ReturnBook = Console.ReadLine();
                    if (BorrowedList.ContainsKey(ReturnBook))
                    {
                        ReturnBook1(ReturnBook);
                    }
                }
                else if (a == 3)
                {
                    foreach (DictionaryEntry item in BorrowedList)
                    {
                        Console.WriteLine(item.Key + " " + item.Value);
                    }
                }
            }

        }
        static void Borrow(string BookName, string name)
        {
            BorrowedList.Add(BookName, name);
        }
        static void ReturnBook1(string BookName)
        {
            BorrowedList.Remove(BookName);
        }
    }
}