C# Library Management console program
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);
}
}
}
}
Answer
You should remove the books by using the bookId or more specifically by the unique Id of the object. Your posted code is removing it from the list using the position of book. The sole purpose of having a bookId is to identify the book from any number of books and then quickly manipulate it using code.
Let me tell you something about Object Oriented Programming (OOP) which will help you some way. Every object has three features in it:
- Identity
- State
- Behavior
Here, Identity (something unique like a bookId which can be used to select it) is the thing that you should use to manipulate your objects (books), not the position of the object.
Enough theory, In your code
bookList.RemoveAt(Del - 1);
is the culprit. Change it to work on the basis of bookId and your problem will be solved.
Thanks