I've been stuck on this for a while and I really need help to understand this program.

Programming problem:

In the Chap07 folder of the Student Sample Programs, you will find a file named ChargeAccounts.txt. The file contains a list of a company's vaild charge account numbers. There are a total of 18 charge account numbers in the file, and each one is a 7-digit number, such as 5658845.

Code:

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO;

namespace Program7_3 { public partial class frmChargeAccount : Form { public frmChargeAccount() { InitializeComponent(); }

const int SIZE = 18; string[] acct= new string[SIZE];

private void Form1_Load(object sender, EventArgs e) { //Read the accounts from a disk file named ChargeAccounts.txt into an array named acct or a List. //Remember the Try statement since you are working with a disk file. StreamReader inputFile;

try { inputFile = File.OpenText("ChargeAccounts.txt");

int intIndex = 0; string strAccountNum = "";

while (!inputFile.EndOfStream==true) { strAccountNum = inputFile.ReadLine();

//put strAccountNum into an array element

intIndex++; } inputFile.Close(); } catch { MessageBox.Show("Problem with disk file."); } }

private void btnCheck_Click(object sender, EventArgs e) { //Iterate through the array or list to see if the account number entered in //the Textbox control is a valid number or not. Display an appropriate message within the lblMessage label.

} } }

Design:

program73 Enter a charge account: d Check