vb.net how do I keep my variable across subs?

Question

how do I keep my variable working when I Click Button1? Can someone help me?

Public Class Form2
    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim Number As Integer
        Randomize()
        Number = Int(Rnd() * 10000000) + 1
        Label2.Text = Number
    End Sub
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        If TextBox1.Text = Number Then
            MsgBox("Correct")
        Else
            MsgBox("Not Correct")
        End If
    End Sub
End Class

`Dim Number As Integer` should be a field of the class `Form2` — Tim Schmelter, Oct 15 '18 at 14:33
Don't use `Randomize` and `Rnd` in VB.NET. Create an instance of the `Random` class and call its `Next` method. Also, you reallu ought to turn `Option Strict On`, both in the project properties and the IDE options, so that it is `On` by default in future projects. — jmcilhinney, Oct 15 '18 at 15:15
The word that no one has mentioned yet is "member". You should be declaring a member variable, also known as a field, rather than a local variable, i.e. declare it outside of any method so that it can be seen from all methods. You should do some reading on scope. When something is declared inside a block then it can only be seen inside that block. — jmcilhinney, Oct 15 '18 at 15:16

score 4 · Answer 1 · answered Oct 15 '18 at 14:35

4

Take your variable and move it as a class variable.

Public Class Form2
    Private Number As Integer ' <-----

    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Randomize()
        Number = Int(Rnd() * 10000000) + 1
        Label2.Text = Number
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        If TextBox1.Text = Number Then
            MsgBox("Correct")
        Else
            MsgBox("Not Correct")
        End If
    End Sub

End Class

With your example, it seems reasonable to do that but I suggest you don't take the habit of doing it to much. I've seen people put almost everything as class variable.

Also, put Option Strict On. It'll save you some headache in the future, as your program gets more complex.

answered Oct 15 '18 at 14:35

the_lotus

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When I try this the program freezes – user10507933 Oct 15 '18 at 14:48
@user10507933 where does it freeze? – the_lotus Oct 15 '18 at 14:55
when i cllick the button – user10507933 Oct 16 '18 at 04:09
Can't reproduce the freeze here. it seems to work just fine. Although it would totally recommend changing your visual studio settings so that option Strict is on for all your projects. It will mean more work when coding, but you'll end up with less problematic code. – David Wilson Oct 16 '18 at 10:21
@user10507933 what happen if you use [MessageBox.Show](https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.messagebox.show?view=netframework-4.7.2) instead ? – the_lotus Oct 16 '18 at 12:50

vb.net how do I keep my variable across subs?

1 Answers1