Textbox only converter - vb.net

Question

I am making a temperature converter in vb.net for my assignment. I know the conversion method and so on.. but the problem is, I need to only use two textboxes. One for Celsius and one for farenheit. Whenever I update the textbox for celsius, the changes on textbox should also happen, and when I change the value for farenheit, the celsius textbox should also change depending on the value for farenheit. What method should I do?
This is the current one im working on..
Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
If TextBox1.Focus() Then
TextBox2.Clear()
TextBox2.Text = (TextBox1.Text - 32) / 1.8
ElseIf TextBox2.Focus() Then
TextBox1.Clear()
TextBox1.Text = (TextBox2.Text * 1.8) + 32
End If
End Sub
End Class

Answer 1

Thanks for posting some code. This is the way I'd do it (after wiring up TextChanged event handlers for both text boxes):
Private DegreesCChanging As Boolean = False
Private DegreesFChanging As Boolean = False
Private Sub DegreesF_TextChanged(sender As Object, e As EventArgs) Handles DegreesF.TextChanged
If Not DegreesFChanging Then
Dim Temperature As Double
DegreesCChanging = True
If Double.TryParse(DegreesF.Text, Temperature ) Then
DegreesC.Text = ((Temperature - 32.0) / 9.0 * 5.0).ToString("0.##")
Else
DegreesC.Text = String.Empty
End If
DegreesCChanging = False
End If
End Sub
Private Sub DegreesC_TextChanged(sender As Object, e As EventArgs) Handles DegreesC.TextChanged
If Not DegreesCChanging Then
Dim Temperature As Double
DegreesFChanging = True
If Double.TryParse(DegreesC.Text, Temperature ) Then
DegreesF.Text = (Temperature / 5.0 * 9.0 + 32.0).ToString("0.##")
Else
DegreesF.Text = String.Empty
End If
DegreesFChanging = False
End If
End Sub
There are a few things to note.
I'm using the TextChanged event - as soon as the user types
something into either text box, the world starts changing
I use double.TryParse to convert the number to a string. If I can't figure out what's going on (i.e., the TryParse call returns False), I stick an empty string in the other text box. It works quite well.
When the user types something into a text box, it causes a TextChanged event that forces new text into the other text box - which will result in a TextChanged event for that control. I use two Boolean flags to prevent this.
I use a custom numeric format string on my ToString calls to limit
the precision to two decimal places.