Question

This Module is mainly to practice If ... Then ... ElseIf ... with creating a project in Visual Basics

1. Open Visual Basic and create a new Project. Select Windows Form New Project window. You will save this project in your CS 3 folder and name it as: yourlastname-firstname-Grader.
2. In this project user inputs three test scores, a button calculates the average and displays the average and grade. Another button clears the entries.
3. Create a form with seven labels, three textboxes and two buttons, similar to below form layout with each control.
4. Here are the properties of the form and each control:
5. Form: change the title of the form to: <Your Name> - Grader
6. Label1, Text: Test1; Name: leave as is, you don’t use labels in the program
7. Label2, Text: Test2; Name: leave as is
8. Label3, Text: Test3; Name: leave as is
9. Label4, Text: Average; Name: leave as is
10. Label5, Text: Grade; Name: leave as is
11. Label6, Text: blank; Name: lblAverage ; BorderStyle: Fixed 3D; AutoSize: False
12. Label7, Text: blank; Name: lblGrade ; BorderStyle: Fixed 3D; AutoSize: False
13. Textbox1, Test: blank; Name: txtTest1
14. Textbox2, Test: blank; Name: txtTest2
15. Textbox3, Test: blank; Name: txtTest3
16. Button1, Text: Calculate Average; Name: btnCalcAvg
17. Button2, Text: Clear; Name: btnClear
18. Write a Visual Basic program that: 1) accepts three scores, 2) computes the average and assigns the grade.
19. You declare four variables as Integer data type. They are: Test1, Test2, Test3, and Average.
20. You create an IF…ELSEIF… structure to assign grades using this logic. Note: No need to create a loop:
21. To assign Letter Grade use this criteria: Average <60, F; Average <70, D; Average < 80, C; Average < 90, B; Average <=100, A.
22. To do this you write the code in Calculate Average button procedure. First declare the variables that will get test scores (intTest1, intTest2, intTest3) from textboxes and another one (intAverage) for calculating the tests average. Then assign textbox entries into the first three variables. Then calculate the Average and finally based on the Average assign a Letter Grade.
23. Clear button clears the entries in Test1, Test2, Test3 textboxes and in Average and Grade labels. Then program is ready to take another set of test scores.Ready to enter another set of numbers.
24. After creating the following form layout in Visual Basics (see assignment 8 on how to create a new project). Make sure to name the controls according to above steps 11 - 17.
25. Double-click on Calculate Average, you will placed in Code window to write code:
26. Declare 4 variables: intTest1, intTest2, intTest3, intAverage as Integer.
27. Assign textbox entries for three scores into intTest1, intTest2, intTest3 variables, Example: intTest1 = txtTest1.Text
28. Calculate Average, develop an expression to sum three tests values and divide by 3. Store Average into intAverage variable.
29. Then develop nested IF … THEN … ELSEIF … ELSEIF selection structure to evaluate Average and assign a Letter Grade.
30. You display the average and assigned grade in Average and Grade label controls
31. We have reviewed similar nested selection structure in Selection slides.
32. You may want to start with a similar code below and make sure to make the necessary changes. Before starting to build IF statement, don’t forget to declare the variables and assign Test1, Test2, Test3 to their corresponding variables. Also calculating the Average of three tests:

     If Average < 60 Then

            lblAvg.Text = Average

            lblGrade.Text = "F"

        ElseIf Average < 70 Then

            lblAvg.Text = Average

            lblGrade.Text = "D"

        ElseIf Average < 80 Then

            lblAvg.Text = Average

            lblGrade.Text = "C"

        ElseIf Average < 90 Then

            lblAvg.Text = Average

            lblGrade.Text = "B"

        ElseIf Average < 100 Then

            lblAvg.Text = Average

            lblGrade.Text = "A"

        End If

33. To program Clear button, double-click on Clear button on the form.
34. Type the code to clear the textboxes and label controls entries:
35. You can use the following sample code:

txtTest1.Text = ""

  lblAvg.Text = ""

lblGrade.Text = ""

                         

Form layout with controls

Answer 1

User Interface frmMain.vb[Design]:

Screen showing controls :

************************************

'This is the VB from
Public Class frmMain
'This is click event for click button
Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click
'When clear button is clicked clear the textbox and labels
lblAverage.Text = "" 'clear average label
lblGrade.Text = "" 'Clear grade label
txtTest1.Text = "" 'Clear Test1 textbox
txtTest2.Text = "" 'Clear Test2 textbox
txtTest3.Text = "" 'Clear Test3 textbox
End Sub
'This is click event for calculate average button
Private Sub btnCalcAvg_Click(sender As Object, e As EventArgs) Handles btnCalcAvg.Click
Dim intTest1 As Integer 'This variable will store score for Test1
Dim intTest2 As Integer 'This variable will store score for Test2
Dim intTest3 As Integer 'This variable will store score for Test3
Dim intAverage As Integer 'This variable will store average for test scores
intTest1 = Integer.Parse(txtTest1.Text) 'Take score for Test1 and convert it into integer
intTest2 = Integer.Parse(txtTest2.Text) 'Take score for Test2 and convert it into integer
intTest3 = Integer.Parse(txtTest3.Text) 'Take score for Test3 and convert it into integer
'This line will calculate average and store this average in the variable intAverage
intAverage = (intTest1 + intTest2 + intTest3) / 3
'Using if else statement in VB to check average of the test scores
If intAverage < 60 Then
'when average of test scores is less than 60 then
lblAverage.Text = intAverage 'print intAverage
lblGrade.Text = "F" 'print grade for avergae less than 60 which is F
ElseIf intAverage < 70 Then
'when average of test scores is less than 70 then
lblAverage.Text = intAverage 'print intAverage
lblGrade.Text = "D" 'print grade for avergae less than 70 which is D
ElseIf intAverage < 80 Then
'when average of test scores is less than 80 then
lblAverage.Text = intAverage 'print intAverage
lblGrade.Text = "C" 'print grade for avergae less than 80 which is C
ElseIf intAverage < 90 Then
'when average of test scores is less than 90 then
lblAverage.Text = intAverage 'print intAverage
lblGrade.Text = "B" 'print grade for avergae less than 90 which is B
ElseIf intAverage < 100 Then
'when average of test scores is less than 100 then
lblAverage.Text = intAverage 'print intAverage
lblGrade.Text = "A" 'print grade for avergae less than 100 which is A
End If
End Sub

End Class
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Screen showing average of three test scores and grade :