How to code this so any text box will compute

[Mykro]

I have a form with 3 text boxes.. txtDiameter.text txtCircumference.text, txtArea.text and btncompute to compute the value entered in txtDiameter that will be displayed in txtCircumference.text and txtArea.text

I have a code module:

 

Module CircGeometry

Public Sub CircleGeometry(ByVal diameter As Double, ByRef Circumference As Double, _

ByRef Area As Double)

Circumference = Math.PI * diameter

Area = Math.PI * diameter ^ 2 / 4

 

End Sub

End Module

 

And here is the btnCompute click event:

 

Private Sub btnCompute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompute.Click

Dim C As Double

Dim A As Double

Dim D As Double

D = Val(txtDiameter.Text)

Call CircleGeometry(D, C, A)

txtCircumference.Text = Format(C, "0.00")

txtArea.Text = Format(A, "0.00")

 

End Sub

End Class

 

What I need help on is this: .. How can I code this so that no matter what text box I enter a value it is calculated in the other text boxes simutaneously.. I don't how to code this...

[DiverDan]

How about this:

 

if txtDiameter.Text <> Nothing then
'compute from diameter
elseif txtArea.Text <> Nothing then
'compute from area
elseif txtCircumference <> nothing then
'compute from circumference
end if

 

you'll probably need to expand the if statements to also watch for only one entry in the three boxes and, of course, restrict the boxes to a numeric entry only.

 

Hope that helps

Dan

[Mykro]

How about this:

 

if txtDiameter.Text <> Nothing then
'compute from diameter
elseif txtArea.Text <> Nothing then
'compute from area
elseif txtCircumference <> nothing then
'compute from circumference
end if

 

you'll probably need to expand the if statements to also watch for only one entry in the three boxes and, of course, restrict the boxes to a numeric entry only.

 

Hope that helps

Dan

 

Thanks for the code But.. It don't work..

 

Maybe you don't quite understand what I want to do..

instead of entering a value in txtdiameter I could put a value in txtArea instead and it will compute and put the correct answers in the other text boxes. Or put a value in txtcircumference and it will calculate for the other text boxes.

[Mothra]

If you use a Button to fire the calculation method, you try this in the Button's Click event...

 

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles Button1.Click
    
       If Not TextBox1.Text = "" And _
              TextBox2.Text = "" And _
              TextBox3.Text = "" Then
              'Calculate whatever
       ElseIf Not TextBox2.Text = "" And _
                  TextBox1.Text = "" And _
                  TextBox3.Text = "" Then
              'Calculate whatever
       ElseIf Not TextBox3.Text = "" And _
                  TextBox1.Text = "" And _
                  TextBox2.Text = "" Then
              'Calculate whatever
       End If

End Sub

 

This way, it will only do your calculations if there are no other values entered.

[Mykro]

If you use a Button to fire the calculation method, you try this in the Button's Click event...

 

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles Button1.Click
    
       If Not TextBox1.Text = "" And _
              TextBox2.Text = "" And _
              TextBox3.Text = "" Then
              'Calculate whatever
       ElseIf Not TextBox2.Text = "" And _
                  TextBox1.Text = "" And _
                  TextBox3.Text = "" Then
              'Calculate whatever
       ElseIf Not TextBox3.Text = "" And _
                  TextBox1.Text = "" And _
                  TextBox2.Text = "" Then

       End If

End Sub

 

This way, it will only do your calculations if there are no other values entered.

 

I'll try your code.. In the mean time this was what I came up with..

just need to clear the text boxes before the next calculation.

 

 

 

Private Sub btnCompute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompute.Click

Dim Circumference As Double

Dim Area As Double

Dim Diameter As Double

Diameter = Val(txtDiameter.Text) 'convert to number

Area = Val(txtArea.Text) 'convert to number

Circumference = Val(txtCircumference.Text) 'convert to number

 

If txtDiameter.Text <> "" Then

Circumference = Math.PI * Diameter

Area = 3.14 * Diameter ^ 2 / 4

 

ElseIf txtCircumference.Text <> "" Then

Area = ((Circumference / 3.14) ^ 2) * 3.14 / 4

Diameter = Circumference / 3.14

 

ElseIf txtArea.Text <> "" Then

Circumference = 2 * Math.Sqrt(Area / 3.14) * 3.14

Diameter = 2 * Math.Sqrt(Area / 3.14)

Else

MessageBox.Show("You Must Enter a Number!", "No Numeric Entry!", MessageBoxButtons.OK, MessageBoxIcon.Hand)

txtDiameter.Focus()

End If

 

txtCircumference.Text = Format(Circumference, "0.00") 'format to display in txt box

txtArea.Text = Format(Area, "0.00") 'format to display in txt box

txtDiameter.Text = Format(Diameter, "0.00") 'format to display in txt box

 

End Sub

 

Private Sub frmCircle_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

txtDiameter.Focus()

 

End Sub

 

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click

txtDiameter.Text = ""

txtCircumference.Text = ""

txtArea.Text = ""

txtDiameter.Focus()

 

End Sub

 

Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click

Me.Close()

 

End Sub

[DiverDan]

Hum, looks like my original example.

But...what happens if the user enters values in two or all boxes? How are you handling a non-numeric entry - it's better to restrict the text box to only numeric entries than display a message box. Along with txtArea.Text = "' you might use txtArea.Clear() or txtArea.Text = Nothing....they're basically all the same.

 

Here's an example of restricting a text box that you might include in you program rather than the message box:

   'Positive Numbers, Dot and Backspace Only
   Private Sub PositiveNumbersDotOnly_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles _
   txtVolts.KeyPress, txtValue.KeyPress

       If AscW(e.KeyChar) = 8 Then 'backspace
           e.Handled = False
           Exit Sub
       End If
       If Not AscW(e.KeyChar) < 46 And Not AscW(e.KeyChar) >= 58 Or AscW(e.KeyChar) = 8 Then
           If sender.Text.IndexOf(".") >= 0 Then
               If sender.SelectedText.Length >= 1 Then
                   e.Handled = False
               ElseIf e.KeyChar = "." Then
                   e.Handled = True
               End If
           End If
       Else : e.Handled = True
       End If
   End Sub

 

also look into the error provider control...it's pretty cool.

[Mykro]

Hum, looks like my original example.

But...what happens if the user enters values in two or all boxes? How are you handling a non-numeric entry - it's better to restrict the text box to only numeric entries than display a message box. Along with txtArea.Text = "' you might use txtArea.Clear() or txtArea.Text = Nothing....they're basically all the same.

 

Here's an example of restricting a text box that you might include in you program rather than the message box:

   'Positive Numbers, Dot and Backspace Only
   Private Sub PositiveNumbersDotOnly_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles _
   txtVolts.KeyPress, txtValue.KeyPress

       If AscW(e.KeyChar) = 8 Then 'backspace
           e.Handled = False
           Exit Sub
       End If
       If Not AscW(e.KeyChar) < 46 And Not AscW(e.KeyChar) >= 58 Or AscW(e.KeyChar) = 8 Then
           If sender.Text.IndexOf(".") >= 0 Then
               If sender.SelectedText.Length >= 1 Then
                   e.Handled = False
               ElseIf e.KeyChar = "." Then
                   e.Handled = True
               End If
           End If
       Else : e.Handled = True
       End If
   End Sub

 

also look into the error provider control...it's pretty cool.

 

Hey Dan.... Could you do me a favor and comment each line of your code..I'm a little fuzzy with it, and good commentation would help me out alot...Thanks :D

[DiverDan]

Firstly, opps I forgot to DirectCast sender in my example and that is not a good habit, sorry. It should be DirectCast(sender, TextBox).Text and DirectCast(sender, TextBox).SelectedItem.

 

The code looks at the keyborad entered keys (KeyChar) and allows only specific keys from being entered into the textboxes.

 

AscW(e.KeyChar) 48 through 58 are the keyboard number keys 0 through 9 while AscW(e.KeyChar) 8 is the keyboard backspace key.

 

Obviously a decimaled number can only contain one dot and the code looks for an instance of the dot in the sender.Text.IndexOf(".") section. If a dot is present then a positive number will be returned referencing its location in the textbox.Text string, otherwise it will return -1 if no dot is present.

 

The SelectedText.Length allows the user to select (highlight) text that contains a dot and either delete it or enter another value. If this section of code was not present then once a dot was entered, the user would not be able to select (hightlight) the textbox and enter a decimal, ie .95.

 

e.Handled = False allows keyboard entry while e.Handled = True stops the keyboard entry.

 

I personally prefer restricting text box entries over annoying message boxes popping up on the screen with a beep. But if the text box can't be restricted then try the ErrorProvider1 control. It flashes a nice red circle with a white little exclamation point in the center, flashes for a bit and displays an appropriate tooltip. Much more preferred by myself.

 

I think that about covers the documentation.

You should still check for a double textbox entry.

 

Dan

Edited December 8, 2003 by DiverDan

[Mykro]

Thanks Dan... :)