How do you change the value in my.settings in a form when you enter numbers in a textbox in VB.Net - vb.net

Question

I was wondering if you could help me? My question is that, is there a way of changing the value in my.Settings in a form if you enter a number/decimal in a textbox and click a button and then update in the settings to be then changed in another from which is linked to my.Settings in a variable?!
Form 1:
Public Class frmConverter
Dim input As String
Dim result As Decimal
Dim EUR_Rate As Decimal = My.Settings.EUR_Rates
Dim USD_Rate As Decimal = 1.6
Dim JYP_Rate As Decimal = 179.65
Private Sub btnCalc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalc.Click
input = txtInput.Text
Try
If ComboBox1.Text = "£" Then
Pounds()
ElseIf ComboBox1.Text = "€" Then
Euros()
ElseIf ComboBox1.Text = "$" Then
Dollars()
ElseIf ComboBox1.Text = "¥" Then
Yen()
End If
Catch es As Exception
MsgBox("Error!")
End Try
End Sub
Private Sub btnSettings_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSettings.Click
Me.Hide()
frmExchange.Show()
End Sub
Private Sub btnReset_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnReset.Click
txtInput.Text = ""
lblResult.Text = ""
End Sub
Function Pounds()
If ComboBox1.Text = "£" And ComboBox2.Text = "€" Then
result = (input * EUR_Rate)
lblResult.Text = FormatNumber(result, 2) & " " & ComboBox2.Text
ElseIf ComboBox1.Text = "£" And ComboBox2.Text = "$" Then
result = (input * USD_Rate)
lblResult.Text = FormatNumber(result, 2) & " " & ComboBox2.Text
ElseIf ComboBox1.Text = "£" And ComboBox2.Text = "¥" Then
result = (input * JYP_Rate)
lblResult.Text = FormatNumber(result, 2) & " " & ComboBox2.Text
End If
Return 0
End Function
Form 2:
Public Class frmExchange
Private Sub frmExchange_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
My.Settings.EUR_Rates = (txtinput.Text)
My.Settings.Save()
My.Settings.Reload()
End Sub
Public Sub SetNewRate(ByVal rate As Decimal)
txtinput.Text = rate.ToString
End Sub
Private Sub btnchange_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnchange.Click
If ComboBox1.Text = "€" Then
My.Settings.USD_Rates = (txtinput.Text)
frmConverter.SetNewRate(txtinput.Text)
End If
End Sub
End class

Answer 1

It sounds like you are trying to use My.Settings as some sort of set of global reference variables. Thats not what they are for, not how they work and not what they are.
First, turn on Option Strict as it looks like it may be Off. This will store the decimal value of a textbox to a Settings variable which is defined as a Decimal:
My.Settings.USD_Rates = CDec(SomeTextBox.Text)
Thats all it will do. It wont save the value and it wont pass it around or share it with other forms and variables.
My.Settings.Save 'saves current settings to disk for next time
My.Settings.Reload 'Load settings from last time
This is all covered on MSDN. There is no linkage anywhere. If you have code in another form like this:
txtRate.Text = My.Settings.USD_Rates.ToString
txtRate will not automatically update when you post a new value to Settings. There are just values not Objects (see Value Types and Reference Types). To pass the new value to another form:
' in other form:
Public Sub SetNewRate(rate As Decimal)
' use the new value:
soemTextBox.Text = rate.ToString
End Sub
in form which gets the change:
Private Sub btnchangeRate(....
' save to settings which has nothing to do with passing the data
My.Settings.USD_Rates = CDec(RateTextBox.Text)
otherForm.SetNewRate(CDec(RateTextBox.Text))
End Sub
You may run into problems if you are using the default form instance, but that is a different problem.
You botched the instructions. The 2 procedures are supposed to go in 2 different forms - one to SEND the new value, one to RECEIVE the new value. With the edit and more complete picture, there is an easier way.
Private Sub btnSettings_Click(...) Handles btnSettings.Click
' rather than EMULATE a dialog, lets DO a dialog:
'Me.Hide()
'frmExchange.Show()
Using frm As New frmExchange ' the proper way to use a form
frm.ShowDialog
' Im guessing 'result' is the xchg rate var
result = CDec(frm.txtInput.Text)
End Using ' dispose of form, release resources
End Sub
In the other form
Private Sub btnchange_Click(....)
' do the normal stuff with Settings, if needed then:
Me.Hide
End Sub