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VB NET Exercise Answers

Exercise A (Button code not shown)

Dim number1 As Integer
Dim number2 As Integer
Dim number3 As Integer = 10
Dim answer As Integer

number1 = 3
number2 = 5

answer = number1 + number2

answer = answer * number3

Textbox1.Text = answer

Exercise B

Dim FirstName As String
Dim LastName As String
Dim FullName As String

FirstName ="Bill"
LastName = "Gates"

FullName = LastName & " " & FirstName

Textbox1.Text = FullName

Exercise C

Dim FirstName As String
Dim MiddleName As String
Dim LastName As String
Dim FullName As String

FirstName ="Bill"
MiddleName = "Henry"
LastName = "Gates"

FullName = FirstName & " " & MiddleName & " " & LastName

Textbox1.Text = FullName

Exercise D

Dim FirstName As String
Dim LastName As String
Dim WholeName As String

FirstName = txtFirstName.Text
LastName = txtLastName.Text

WholeName = FirstName & " " & LastName

txtWholeName.Text = WholeName

Exercise E

Dim ButtonContents As String
ButtonContents = Button1.Text

txtVariables.Text = ButtonContents

Exercise F

View the full code for the calculator

Exercise G

Dim agerange As Integer

agerange = Val(textbox1.Text)

Select Case agerange

Case 13 To 19

MessageBox.Show( “In your Teens”)

Case 20 To 29

MessageBox.Show(“In your Twenties”)

Case 30 To 39

MessageBox.Show(“In Thirties ”)

Case Else

MessageBox.Show(“Not at a teen and over 39”)

End Select

Section 3, Part One

Dim number_in_textbox As Integer

number_in_textbox = Val(TextBox1.Text)

If number_in_textbox > 10 And number_in_textbox < 20 Then

MessageBox.Show("Number entered was: " & number_in_textbox)

Else

MessageBox.Show("Number entered was not between 10 and 20")
TextBox1.Text = ""

End If

Section 3, Part Two

Item One, Item Two, Item Three below can be replaced by whatever items you have in your Combo Box list.

Dim MyVariable As String

MyVariable = ComboBox1.Text

Select Case MyVariable

Case "Item One"

MessageBox.Show("You like " & MyVariable & ", I see - good choice")

Case "Item Two"

MessageBox.Show("Really? " & MyVariable & "?")

Case "Item Three"

MessageBox.Show(MyVariable & "? Now you're just being silly!")

End Select

Exercise H

Dim startNumber As Integer
Dim endNumber As Integer
Dim i As Integer
Dim answer As Integer

startNumber = Val(TextBox1.Text)
endNumber = Val(TextBox2.Text)

If startNumber = 0 Or endNumber = 0 Then

MessageBox.Show("Empty textbox")
Exit Sub

End If

For i = startNumber To endNumber

answer = answer + i

Next i

MessageBox.Show(answer)

Exercise I

Dim message As String = ""
Dim counter As Integer = 0

If CheckBox1.CheckState = CheckState.Checked Then

message = message & CheckBox1.Text & vbNewLine
counter = counter + 1

End If

If CheckBox2.CheckState = CheckState.Checked Then

message = message & CheckBox2.Text & vbNewLine
counter = counter + 1

End If

If CheckBox3.CheckState = CheckState.Checked Then

message = message & CheckBox3.Text & vbNewLine
counter = counter + 1

End If

If CheckBox4.CheckState = CheckState.Checked Then

message = message & CheckBox4.Text & vbNewLine
counter = counter + 1

End If

If CheckBox5.CheckState = CheckState.Checked Then

message = message & CheckBox5.Text & vbNewLine
counter = counter + 1

End If

MessageBox.Show("You have chosen " & vbNewLine & message)

Select Case counter

Case 0

MessageBox.Show("You obviously don’t watch soaps!")

Case 1

MessageBox.Show("only 1 show watched")

Case 2

MessageBox.Show("2 shows watched")

Case 3

MessageBox.Show("3 shows watched")

Case 4

MessageBox.Show("4 shows watched")

Case 5

MessageBox.Show("a soap addict")

End Select

Exercise J

Tricky one, this. The solution is to change this line:

letter = strText.Substring(1)

to this:

letter = strText.Substring(i)

By using the loop variable i you advanced the counter for Substring.

Exercise K

Dim OneCharacter As Char
Dim FirstName As String
Dim i As Integer
Dim TextLength As Integer

FirstName = txtChars.Text
TextLength = FirstName.Length

For i = 0 To TextLength - 1

OneCharacter = FirstName.Chars(i)

If IsNumeric(OneCharacter) Then

MessageBox.Show("Number Found - Exiting")
Exit Sub

End If

Exercise L

Dim OneCharacter As Char
Dim FirstName As String
Dim i As Integer
Dim TextLength As Integer
Dim numbercount As Integer = 0

FirstName = txtChars.Text
TextLength = FirstName.Length

For i = 0 To TextLength - 1

OneCharacter = FirstName.Chars(i)

If IsNumeric(OneCharacter) Then

numbercount = numbercount + 1

End If

MessageBox.Show("found " & numbercount & " numbers")

Exercise M

Checking for a valid email address is quite tricky. In the code below, the Sub is just checking if the email address has an @ sign. Notice that the Sub uses two paramaters, one to pass in the email address and one to pass in the @ sign. You can then reuse this code to pass in, say, an email address and the characters ".com"

'===================================
' BUTTON CODE
'===================================
Dim email As String
Dim chars_to_check As Char

email = txtEmail.Text
chars_to_check = "@"

TestEmail1(email, chars_to_check)

'===================================
' SUBROUTINE
'===================================
Private Sub TestEmail1( eMail As String, CheckChars As String)

Dim position As Integer

position = InStr(eMail, CheckChars)

If position = 0 Then

MessageBox.Show("Not a Valid email address")

End If

End Sub

Exercise N

Private Sub TextBox1_Leave( sender As Object, e As EventArgs) Handles TextBox1.Leave

Dim CheckTextBox As String

CheckTextBox = Trim(TextBox1.Text)
CheckTextBox = StrConv(CheckTextBox, VbStrConv.ProperCase)
TextBox1.Text = CheckTextBox

End Sub

Exercise O

Here are the Set and Get properties that change the height and width. (As was mentioned in the text, however, the name of the Class (ConvertPostcode) is not a very good name for what this does - changing the height and width of an image! Plus, picture boxes already have a height and width property)

Private intHeight As Integer
Private intWidth As Integer

Public Property ChangeHeight() As Integer

Get

Return intHeight

End Get

Set( HeightValue As Integer)

intHeight = HeightValue

End Set

End Property

Public Property ChangeWidth() As Integer

Get

Return intWidth

End Get

Set( WidthValue As Integer)

intWidth = WidthValue

End Set

End Property

And here is the code for the button that uses the two properties:

Dim objAlterPicPox As ConvertPostcode
Dim NewHeight As Integer
Dim NewWidth As Integer

objAlterPicPox = New ConvertPostcode

objAlterPicPox.ChangeHeight = Val(txtHeight.Text)
NewHeight = objAlterPicPox.ChangeHeight
PictureBox1.Height = NewHeight

objAlterPicPox.ChangeWidth = Val(txtWidth.Text)
NewWidth = objAlterPicPox.ChangeWidth
PictureBox1.Width = NewWidth

objAlterPicPox = Nothing

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