In this code when I add 2 books and try to delete 1st and 2nd book, 1st gets deleted and 2nd one didn't. In next case when I add 3 books and delete one by one 1 gets deleted and 2 not and 3rd one becomes missing when I delete 2. When I add 4 books 2 and 4 not deleted.
My code (I'm a trainee so I'm a beginner in C#)
using System;
using System.Collections.Generic;
namespace LibraryManagement
{
//Defining a class Book
class Book
{
public int bookId;
public string bookName;
public int bookPrice;
public int bookCount;
public int x;
}
//Defining a class Borrow
class BorrowDetails
{
public int userId;
public string userName;
public string userAddress;
public int borrowBookId;
public DateTime borrowDate;
public int borrowCount;
}
class Program
{
static List<Book> bookList = new List<Book>();
static List<BorrowDetails> borrowList = new List<BorrowDetails>();
static Book book = new Book();
static BorrowDetails borrow = new BorrowDetails();
//Password verfication and Menu
static void Main(string[] args)
{
Console.Write("Welcome !!!\nEnter your password :");
string password = Console.ReadLine();
if (password == "sync")
{
bool close = true;
while (close)
{
Console.WriteLine("\nMenu\n" +
"1)Add book\n" +
"2)Delete book\n" +
"3)Search book\n" +
"4)Borrow book\n" +
"5)Return book\n" +
"6)Close\n\n");
Console.Write("Choose your option from menu :");
int option = int.Parse(Console.ReadLine());
if (option == 1)
{
GetBook();
}
else if (option == 2)
{
RemoveBook();
}
else if (option == 3)
{
SearchBook();
}
else if (option == 4)
{
Borrow();
}
else if (option == 5)
{
ReturnBook();
}
else if (option == 6)
{
Console.WriteLine("Thank you");
close = false;
break;
}
else
{
Console.WriteLine("Invalid option\nRetry !!!");
}
}
}
else
{
Console.WriteLine("Invalid password");
}
Console.ReadLine();
}
//To add book details to the Library database
public static void GetBook()
{
Book book = new Book();
Console.WriteLine("Book Id:{0}", book.bookId = bookList.Count + 1);
Console.Write("Book Name:");
book.bookName = Console.ReadLine();
Console.Write("Book Price:");
book.bookPrice = int.Parse(Console.ReadLine());
Console.Write("Number of Books:");
book.x = book.bookCount = int.Parse(Console.ReadLine());
bookList.Add(book);
}
//To delete book details from the Library database
public static void RemoveBook()
{
Book book = new Book();
Console.Write("Enter Book id to be deleted : ");
int Del = int.Parse(Console.ReadLine());
if (bookList.Exists(x => x.bookId == Del))
{
bookList.RemoveAt(Del - 1);
Console.WriteLine("Book id - {0} has been deleted", Del);
}
else
{
Console.WriteLine("Invalid Book id");
}
bookList.Add(book);
}
//To search book details from the Library database using Book id
public static void SearchBook()
{
Book book = new Book();
Console.Write("Search by BOOK id :");
int find = int.Parse(Console.ReadLine());
if (bookList.Exists(x => x.bookId == find))
{
foreach (Book searchId in bookList)
{
if (searchId.bookId == find)
{
Console.WriteLine("Book id :{0}\n" +
"Book name :{1}\n" +
"Book price :{2}\n" +
"Book Count :{3}", searchId.bookId, searchId.bookName, searchId.bookPrice, searchId.bookCount);
}
}
}
else
{
Console.WriteLine("Book id {0} not found", find);
}
}
//To borrow book details from the Library
public static void Borrow()
{
Book book = new Book();
BorrowDetails borrow = new BorrowDetails();
Console.WriteLine("User id : {0}", (borrow.userId = borrowList.Count + 1));
Console.Write("Name :");
borrow.userName = Console.ReadLine();
Console.Write("Book id :");
borrow.borrowBookId = int.Parse(Console.ReadLine());
Console.Write("Number of Books : ");
borrow.borrowCount= int.Parse(Console.ReadLine());
Console.Write("Address :");
borrow.userAddress = Console.ReadLine();
borrow.borrowDate = DateTime.Now;
Console.WriteLine("Date - {0} and Time - {1}", borrow.borrowDate.ToShortDateString(), borrow.borrowDate.ToShortTimeString());
if (bookList.Exists(x => x.bookId == borrow.borrowBookId))
{
foreach (Book searchId in bookList)
{
if (searchId.bookCount >= searchId.bookCount - borrow.borrowCount && searchId.bookCount - borrow.borrowCount >= 0)
{
if (searchId.bookId == borrow.borrowBookId)
{
searchId.bookCount = searchId.bookCount - borrow.borrowCount;
break;
}
}
else
{
Console.WriteLine("Only {0} books are found", searchId.bookCount);
break;
}
}
}
else
{
Console.WriteLine("Book id {0} not found", borrow.borrowBookId);
}
borrowList.Add(borrow);
}
//To return borrowed book to the library
public static void ReturnBook()
{
Book book = new Book();
Console.WriteLine("Enter following details :");
Console.Write("Book id : ");
int returnId = int.Parse(Console.ReadLine());
Console.Write("Number of Books:");
int returnCount = int.Parse(Console.ReadLine());
if (bookList.Exists(y => y.bookId == returnId))
{
foreach (Book addReturnBookCount in bookList)
{
if (addReturnBookCount.x >= returnCount + addReturnBookCount.bookCount)
{
if (addReturnBookCount.bookId == returnId)
{
addReturnBookCount.bookCount = addReturnBookCount.bookCount + returnCount;
break;
}
}
else
{
Console.WriteLine("Count exists the actual count");
break;
}
}
}
else
{
Console.WriteLine("Book id {0} not found", returnId);
}
}
}
}
The problem is that when you remove a book, your booklist is being reordered so the book ids no longer reflect the position that they were in when you added them. E.g. your bookList has 2 books (bookList[0] and bookList[1]). When you delete 1 book, you are left with booklist[0], so when you try and delete the next book (with your code it says you using del -1 to get the position) you are then trying to delete from your array at bookList[1] which of course, does not exist.