This is from the Starting out with Visual Basic 2010 5th edition book by Gaddis,

Question

This is from the Starting out with Visual Basic 2010 5th edition book by Gaddis, it is from chapter 8, question #4 in programming challenges. The answer is not complete though in the answers for the book, they only created the 1st form for it.

The local Registry of Motor Vehicles office has asked you to create an application

that grades the written portion of the driver’s license exam. The exam has 20 multi-

ple choice questions. Here are the correct answers to the questions:

1. B 6. A 11. B 16. C

2. D 7. B 12. C 17. C

3. A 8. A 13. D 18. B

4. A 9. C 14. A 19. D

5. C 10. D 15. D 20. A

Your application should store the correct answers in an array. A form, such as the

one shown in Figure 8-48, should allow the user to enter answers for each question.

When the user clicks the Score Exam button, the application should display another

form showing whether each question was answered correctly or incorrectly, and

whether the student passed or failed the exam. A student must correctly answer 15

of the 20 questions to pass the exam.

Input validation: Only accept the letters A, B, C, or D as answers.

Explanation / Answer

Here is the 100% working code

Private Sub btnScore_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnScore.Click

'Correct answers as an array

Dim achrCorrectAnswers() As String = {"B", "D", "A", "A", "C", "A", "B", "A", "C", "D", "B", "C", "D", "A", "D", "C", "C", "B", "D", "A"}

Dim achrUserAnswers(19) As String 'Textboxes as an array

achrUserAnswers(0) = txt1.Text

achrUserAnswers(1) = txt2.Text

achrUserAnswers(2) = txt3.Text

achrUserAnswers(3) = txt4.Text

achrUserAnswers(4) = txt5.Text

achrUserAnswers(5) = txt6.Text

achrUserAnswers(6) = txt7.Text

achrUserAnswers(7) = txt8.Text

achrUserAnswers(8) = txt9.Text

achrUserAnswers(9) = txt10.Text

achrUserAnswers(10) = txt11.Text

achrUserAnswers(11) = txt12.Text

achrUserAnswers(12) = txt13.Text

achrUserAnswers(13) = txt14.Text

achrUserAnswers(14) = txt15.Text

achrUserAnswers(15) = txt16.Text

achrUserAnswers(16) = txt17.Text

achrUserAnswers(17) = txt18.Text

achrUserAnswers(18) = txt19.Text

achrUserAnswers(19) = txt20.Text

Dim intCorrect As Integer = 0

For x As Integer = 0 To 19

If achrCorrectAnswers(x) = achrUserAnswers(x) Then

achrUserAnswers(x) = "Correct"

intCorrect += 1

Else

achrUserAnswers(x) = "Incorrect"

End If

Next

Dim AnswersForm As New frmAnswers

AnswersForm.lstAns.Items.AddRange(achrUserAnswers)

'Display the total incorrect answers in the listbox

AnswersForm.lstAns.Items.Add("You have a total of " & (20 - intCorrect).ToString() & " Incorrect answers.")

'Display the total correct answers in the listbox

AnswersForm.lstAns.Items.Add("and a total of " & intCorrect.ToString() & " Correct answers.")

'If the user has 15 or more correct answers, then the user pass the exam

If intCorrect > 14 Then

AnswersForm.lstAns.Items.Add("Congratulations! You have passed the Driver's License Exam.")

'Else, the user fail the exam

Else

AnswersForm.lstAns.Items.Add("You have failed the Driver's License Exam. Try Again.")

End If

'Display the results in another form

AnswersForm.ShowDialog()

End Sub

to restrict user input, set your textboxes maxlength property to 1 + charactercasing property to Upper, then add this code:

Private Sub txt1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txt9.KeyPress, txt8.KeyPress, txt7.KeyPress, txt6.KeyPress, txt5.KeyPress, txt4.KeyPress, txt3.KeyPress, txt20.KeyPress, txt2.KeyPress, txt19.KeyPress, txt18.KeyPress, txt17.KeyPress, txt16.KeyPress, txt15.KeyPress, txt14.KeyPress, txt13.KeyPress, txt12.KeyPress, txt11.KeyPress, txt10.KeyPress, txt1.KeyPress

If Not "ABCD".Contains(Char.ToUpper(e.KeyChar)) AndAlso Not Char.IsControl(e.KeyChar) Then

e.Handled = True

End If

End Sub

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Cheers!!!

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