"Confessor" wrote:

> *Confessor nods*
>
> Okay, I've got a hell of a lead on how to read/write to Random Access
> files, but there's a small problem that's stopping me short of sussing
> out that whole thing.
>
> The "arrowed" line of code (as well as the two lines following, if I skip
> the first/second by commenting) pops the error 'Object reference not set
> to an instance of an object,' no matter what I input into the textbox.
>
> The problem can't be (MaxPoint), since Label5.Text confirms that it's
> value is 1 prior to the execution of Button1_Click, and since no code (as
> of yet) even *creates* points.dat, there's no situation in which its
> value can be anything other than 1 following Form1_Load.
>
> (Note that I've used ... to excise boring, simple parts in the following
> code.)
>
>     Structure PointTemplate
>         Dim Latitude As Single
>         Dim Longitude As Single
>         Dim Elevation As Integer
>     End Structure
>     Dim MaxPoint As Integer
>     Dim Point() As PointTemplate
>
>     Private Sub Form1_Load(...) Handles MyBase.Load
>         If IO.File.Exists("C:\...\points.dat") Then
>         Else
>             MaxPoint = 1
>         End If
>         Label5.Text = MaxPoint
>     End Sub
>
>     Private Sub Button1_Click(...) Handles Button1.Click
> --->    Point(MaxPoint).Latitude = TextBox2.Text    <---
>         Point(MaxPoint).Longitude = TextBox3.Text
>         Point(MaxPoint).Elevation = TextBox4.Text
>         MaxPoint = MaxPoint + 1
>     End Sub
>
> Thanks in Advance,
> The Confessor
>

"Confessor" wrote:

> "=?Utf-8?B?S2VycnkgTW9vcm1hbg==?="
> <KerryMoor***@discussions.microsoft.com> wrote in
> news:0E485F23-FAC4-4F24-B676-193F4668B974@microsoft.com:
>
> > I don't see where you have dimensioned your Point array to have any
> > elements.
> >
> > So you can't refer to Point (MaxPoint), where MaxPoint is 1, since
> > there is no element 1 in the Point array.
> >
> > Kerry Moorman
> >
>
> So,
>
> ---> Dim Point([any frickin' number]) As PointTemplate <---
>
> will do it, eh? Makes sense. Don't recall having this problem in a previous
> project, but I'd forgotten that I'd specifically dimensioned that
> particular array to (85)
>
> Rather discouraging, as I was planning on having a variable "cap" for the
> array, such that the upper limit would always be equal to the current
> MaxPoint.
>
> And if I set Point() to an insane cap like 2000000, I'll have to institute
> a check prior to each write for null values of Point(T).[Structure
> Members], just to minimize storage.
>
> Hmm... It's enough to make me give a shot at understanding Serializeable
> Classes
>
> Thanks for your help,
>
> The Confessor
>

news:EA629DDE-A96D-4548-AF8B-E6DB0F8E36DD@microsoft.com:

> Confessor,
>
> Once you know the array size that you need you can use the REDIM
> command to create an array of the appropriate size. Or you can use
> REDIM PRESERVE to increase the array size as needed, while preserving
> the current elements.
>
> Kerry Moorman