Use a textbox to store a numeric counter in VB.Net - vb.net

Question

I want to count with a TextBox.
Here is my code:
Public Class Form1
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
OrainsProgressBar1.Increment(1)
If OrainsProgressBar1.Value = 100 Then
Timer3.Start()
Timer1.Stop()
End If
End Sub
Private Sub OrainsTheme1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OrainsTheme1.Click
End Sub
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Timer1.Start()
Timer2.Start()
End Sub
Private Sub Timer3_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer3.Tick
OrainsProgressBar1.Increment(-1)
If OrainsProgressBar1.Value = 0 Then
Timer1.Start()
Timer3.Stop()
End If
End Sub
Private Sub OrainsButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OrainsButton1.Click
OrainsTextBox1.Text += 100
End Sub
Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
OrainsTextBox1.Text += 1
End Sub
End Class
But I have an error with OrainsTextBox1.Text += 1. VB says:
'Conversion from string "" to type 'Double' is not valid.'
What is the problem?

Answer 1

In the .Net world, the data types of things matter a lot. Strings (like the .Text property) are NOT numbers. You need to convert. Even if someone only enters the digits 0-9 into the textbox, that's still a string of numeric characters, rather than a number. And what should happen if someone enters random text into that textbox that won't convert to a number type at all?
For this code, I suggest building a property, like this:
Private _orainsValue As Double
Public Property OrainsValue As Double
Get
Return _orainsValues
End Get
Set
_orainsValue = Value
OrainsTextBox1.Text = _orainsValue.ToString()
End Set
End Property
That will let you write code like this and have the expected result shown to the user:
Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
OrainsVale += 1
End Sub
Note that it does mean you will want to mark the TextBox disabled,though, because this doesn't account for user data entry.

Answer 2

Instead of doing like this OrainsTextBox1.Text += 1
do like this OrainsTextBox1.Text = Val(OrainsTextBox1.Text) + 1
Because .Text is string. Which will append the 1s as "11111111"