This document contains code for a console bookstore application backend. It includes functions for displaying menus, purchasing books, reserving books, and validating user input. The main function initializes variables and displays an intro screen before running a loop to get user input and call the appropriate function for that selection, such as purchasing a book which would validate inputs, calculate totals, and display a receipt. Other functions validate dates, calculate taxes, and clear the console screen between menus.

1. /*============== Vulcan Values Console Bookstore Application (Back-end) =============*/
using System;
using System.Text.RegularExpressions;
namespace VulcanBookStore
{
class Bookstore
{
static void Main(string[] args)
{
/*============== Initialize All Variables =============*/
int iSelected = 0;
double total = 0;
/*------------- Begin Console Settings ----------------*/
Console.BackgroundColor = ConsoleColor.White;
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Clear();
Console.WindowWidth = 95;
Console.WindowHeight = 35;
/*------- Begin Writing-Show the Welcome Message ------*/
Console.Write("nn Welcome to your local community bookstore, " +
"n where you will find the best book prices on the planet!" +
"nn Vulcan Values Bookstore n The Logical Choice LLAP" +
"nn *** Main Menu Screen ***nn 1. Purchase a book " +
"n 2. Reserve a book n 3. Add a book n 4. Edit a book n " +
"5. Delete a book n 6. Exit nnnn Enter your choice: ");
Back to Resume Page

2. /*---------------- Begin Selection Input---------------*/
do
{
string strSelection = Console.ReadLine();
int.TryParse(strSelection, out iSelected);
switch (iSelected)
{
case 1:
total = PurchaseBook();
DisplayTotal(total);
DisplayMenu();
break;
case 2:
DisplayReports();
DisplayMenu();
break;
case 3:
Inventory("Add a book");
DisplayMenu();
break;
case 4:
Inventory("Edit a book");
DisplayMenu();
break;
case 5:
Inventory("Delete a book");
DisplayMenu();
break;
case 6:
Console.Write("nnnnn Please press any key to exit the program => "+
"n (EOP) CSingleton ");
Console.ReadKey();
break;
default:
Console.Clear();
DisplayMenu();
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("Your choice is invalid.");
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("n Please enter a number between 1 and 6 (Inclusive): ");
break;
}
}
while (iSelected != 6);
}

3. private static void DisplayMenu()
{
Console.ForegroundColor = ConsoleColor.DarkBlue;
string[] array = new string[7] {" 1. Purchase a book", "n 2. Reserve a book", "n 3. Add a book",
"n 4. Edit a book", "n 5. Delete a book", "n 6. Exit",
"nnnn Enter your choice: " };
Console.Write("nnnnn Vulcan Values Bookstore n The Logical Choice LLAP" +
"nn *** Main Menu Screen ***nn");
for (int i = 0; i < array.Length; ++i)
{
Console.Write(array[i]);
}
}
private static void Inventory(string bookChoice)
{
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("You selected: {0} " +
"nn Please press any key to continue =>", bookChoice);
Console.ReadKey();
Console.Clear();
}
private static double PurchaseBook()
{
/*============== Initialize All Variables =============*/
string strIsbnPurchase = "", bookTitle = "", qNumString = "", pNumString = "";
int quantity = 0;
double price = 0, tax = 0, subTotal = 0, total = 0;
const double TAX_RATE = 0.091;
bool valQuantity = false;
/*------------------- BookStore Header ---------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Clear();
Console.Write("n Vulcan Values Bookstore --- The Logical Choice LLAP" +
"nn ****** Purchase Book Information Screen ******nn");

4. /****************** Begin user inputs *****************/
/*----------------------- Date -----------------------*/
Console.Write("nn Date (mm/dd/yyyy): ");
string myDate = Console.ReadLine();
Regex reg = new Regex("^(0[1-9]|1[012])[/](0[1-9]|[12][0-9]|3[01])[/](19|20)dd+$");
while (!reg.IsMatch(myDate))
{
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Clear();
Console.Write("n Vulcan Values Bookstore --- The Logical Choice LLAP" +
"nn ****** Purchase Book Information Screen ******nn");
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("n Some of the date did not come out right." +
" Please put the date in again. ");
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("n Date (mm/dd/yyyy): ");
myDate = Console.ReadLine();
}
/*The code below that is commented out is for date string validation using the parse method.*//*
Console.Write("nn Date (mm/dd/yyyy): ");
myDate = Console.ReadLine();
if (myDate == "")
{
DateTime result;
dateString = "10/13/2015";
format = "d";
CultureInfo provider = CultureInfo.InvariantCulture;
result = DateTime.ParseExact(dateString, format, provider);
System.Globalization.CultureInfo MyCultureInfo = new System.Globalization.CultureInfo("en-US");
DateTime MyDateTime = DateTime.Parse(myDate, MyCultureInfo);
}
else
{
DateTime result;
dateString = "11/30/2015";
format = "d";
CultureInfo provider = CultureInfo.InvariantCulture;
result = DateTime.ParseExact(dateString, format, provider);
System.Globalization.CultureInfo MyCultureInfo = new System.Globalization.CultureInfo("en-US");
DateTime MyDateTime = DateTime.Parse(myDate, MyCultureInfo);
}

5. *//*--------------------- Quantity ----------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Quantity: ");
qNumString = Console.ReadLine();
int.TryParse(qNumString, out quantity);
if (quantity <= 0)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("Please enter a positive number larger than zero.n");
}
/*--------------------- ISBN Number ---------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" ISBN: ");
strIsbnPurchase = Console.ReadLine();
if (strIsbnPurchase == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("Please enter a valid ISBN. nn");
}
/*-------------------- Book Title ----------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Title: ");
bookTitle = Console.ReadLine();
if (bookTitle == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("Please enter an valid Title. nn");
}
/*-------------------- Retail Price --------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Price: ");
pNumString = Console.ReadLine();
double.TryParse(pNumString, out price);
if (price < 0 || String.IsNullOrEmpty(pNumString))
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("Please enter zero or a number larger than zero.n");
}

6. /*------------------- Begin Calculations ------------------*/
subTotal = quantity * price;
tax = subTotal * TAX_RATE;
total = subTotal + tax;
/*------------ Assign value to boolean variable ----------*/
//Flag is set if these conditions are met, then do not process the sales slip.
valQuantity = quantity <= 0 || price < 0 || bookTitle == ""
|| strIsbnPurchase == "" || String.IsNullOrEmpty(pNumString);
if (valQuantity)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("nnnnnCould not process the sales slip, as some of the " +
"data was invalid.nPlease try again later.");
}
else
{
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("nn Vulcan Values Bookstore --- The Logical Choice LLAPnn Date: {0}" +
"nnn Qty ISBN Title Price Totaln" +
" ___________________________________________________________________________________" +
"n {1,-6} {2,-14} {3,-32} {4,-8:C2}{5,13:C2}nn " +
" Subtotal: {6,28:N2}n Tax(9.1%): {7,27:N2}" +
"n Total: {8,31:C2}nn " +
" Thank You For Shopping at Vulcan Values Bookstore!"
, myDate, quantity, strIsbnPurchase, bookTitle, price, subTotal
, subTotal, tax, total);
}
/*--------------- Display the total purchased --------------*/
if (valQuantity)
{
total = 0;
return total;
}
else
{
return total;
}
}

7. private static void DisplayTotal(double purchaseTotal)
{
int quantity = 0;
double price = 0;
bool valQty = false;
valQty = quantity <= 0 || price < 0;
if (valQty)
{
Console.ForegroundColor = ConsoleColor.DarkGreen;
Console.Write("nnn Your purchase total amount is: {0:c}", purchaseTotal);
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("nn Please press any key to continue => ");
Console.ReadKey();
Console.Clear();
}
else
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("nnn Your purchase total amount can not be calulated " +
"because of invalid data entered"
+ "nn Please press any key to continue => ");
Console.ReadKey();
Console.Clear();
}
}
private static void DisplayReports()
{
/*================ Initialize All Variables =================*/
//Flag is set if these conditions are met, then do not process the book reservation slip.
string resIsbn = "", resBookTitle = "", strWholeSaleCost = ""
, publisherInfo = "", authorInfo = "";
double wholeSaleCost = 0;
bool resDataNotValid = false;
/*------------------ Begin Write Statements -----------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Clear();
Console.Write("nn Vulcan Values Bookstore --- The Logical Choice LLAPnn" +
" *** Book Reservation Screen ***");

8. /********************** Begin User Inputs ********************/
/*-------------------------- ISBN ---------------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("nn ISBN(13): ");
resIsbn = Console.ReadLine();
if (resIsbn == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("You need to enter an valid ISBN. nn");
}
/*---------------------- Book Title -------------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Title: ");
resBookTitle = Console.ReadLine();
if (resBookTitle == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("You need to enter an valid Title. nn");
}
/*----------------------- Author Info -----------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Author: ");
authorInfo = Console.ReadLine();
if (authorInfo == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("You need to enter an valid Author. nn");
}
/*------------------------Publisher Info ---------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" Publisher: ");
publisherInfo = Console.ReadLine();
if (publisherInfo == "")
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("You need to enter a valid Publisher. nn");
}

9. /*---------------------- WholeSale Cost ----------------------*/
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write(" WholeSale Cost: ");
strWholeSaleCost = Console.ReadLine();
double.TryParse(strWholeSaleCost, out wholeSaleCost);
if (wholeSaleCost <= 0 || String.IsNullOrEmpty(strWholeSaleCost))
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("You must enter a number larger than zero.n");
}
/*------------------- Invalid Data Handling ------------------*/
resDataNotValid = (wholeSaleCost <= 0 || resIsbn == "" || resBookTitle == ""
|| authorInfo == "" || publisherInfo == "");
if (resDataNotValid)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.Write("nnnnnIncorrect data was entered and " +
"the book could not be reserved.");
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.WriteLine(" nnnnnnn " +
"Please press any key to continue =>");
Console.ReadKey();
Console.Clear();
}
else
{
/*-------------------- Process the sales slip -------------------*/
{
Console.ForegroundColor = ConsoleColor.DarkBlue;
Console.Write("nnnn The following book has been requested: n Title: {0}, " +
"Author: {1} n ISBN: {2}, Publisher: {3}, Cost: {4:C2}n"
, resBookTitle, authorInfo, resIsbn, publisherInfo, wholeSaleCost);
/*---------------- Display the Final Message ----------------*/
Console.Write("nn Thank you for doing business with Vulcan Values Bookstore.n " +
"We are committed to reducing our carbon footprint.n We use recyclable products! " +
"Save our planet! LLAPnnn Please press any key to continue => ");
/*---------------- Redisplay the selection screen ------------*/
Console.ReadKey();
Console.Clear();
}
}
}
}
}