Variables declarations: What's the difference? (RESOLVED)

[AlvaroF1]

What's the difference between it:

Public Class Form1
    Inherits System.Windows.Forms.Form
    Dim myVar As String = "Some text" 'Variable declaration here
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        MsgBox(myVar)
    End Sub
End Class

And it:

Public Class Form1
    Inherits System.Windows.Forms.Form
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim myVar As String = "Some text" 'Variable declaration here
        MsgBox(myVar)
    End Sub
End Class

?

Thanks.

[Memnoch1207]

the first one is declared as a class level variable, so it can be used throughout the entire class.

The second one is declared within a sub, so it is a block level variable and can only be used within the block or sub it was declared in.

[Edneeis]

The scope. The first one enables the variable to be used anywhere in the form. The second one means the variable is only valid within the Button click event.

[The Phoenix]

By way of example, here's a code snippet from a project a did last semester in college:

'''''
    'The Timer variable for the progress bar
    Private pinttime As Integer = 0
 
    Private Sub tmrSplash_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrSplash.Tick
        pgrProgress.Value += 1
        pinttime = pinttime + 1
        '''''
        'When the timer hits the maximum value of
        'the progress bar, close the form
        If pinttime = pgrProgress.Maximum Then
            Me.Close()
            tmrSplash.Dispose()
        End If
    End Sub

If the "Private pinttime As Integer = 0" was in the "Private Sub" section, the value would be reset to 0 every time the timer ticked, but since I want the timer to keep increasing, I put the variable before the procedure.

They are correct, I just thought an example might be helpful.

[Kasracer]

I'd suggest reading a book. Learning the scope of things is very helpful in all languages.

Variables in functions in VB, C++, and most other languages, they are local to that function, it's in that function's scope.

[AlvaroF1]

What about CPU and memory usage?


Thanx.

[Edneeis]

Originally posted by AlvaroF1
What about CPU and memory usage?


Thanx.

What about them? Learning and using the proper scope will improve memory usage.

[Kasracer]

Originally posted by AlvaroF1
What about CPU and memory usage?


Thanx.