Gaddis Starting Out With Visual C#, 4th edition, Chapter 7 pg. 468, question #3 Charge Account Validation. Constraints: It must use a string value-returning method, name FAccNum, and return an appropriate message if it found it or not. It will also create a string parameter named FAccNum. The Textbox Control's KeyPress event to be coded so only 0 through 9 digits are entered with the backspace key.

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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.

}

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.

} } }