CODEWITHSUNDEEP
vb.netvariables
John
John

Reputation: 1338

in vb.net how do I use a variable in a variable name

I have a bunch of variables named "panel_1", panel_2", etc and I want to change the height of all of the controls using a loop rather than naming each one.

Currently I use

Dim panel_1 as new panel
Dim panel_2 as new panel
Dim panel_3 as new panel

panel_1.height = 100
panel_2.height = 100
panel_3.height = 100

How can I do it this way?

for x as integer = 0 to 1000
  panel_[x].height = 100
next

thanks.

Upvotes: 0

Views: 7871

Answers (4)

DNKROZ
DNKROZ

Reputation: 2872

Just loop through how many panels you want (In your case 3) & create a new panel on each iteration, setting the height & name programmatically. 

For i = 0 To 3
  Dim panel As New Panel
  panel.Name = "panel" & i
  panel.Height = 100
Next

Upvotes: 0

Ňɏssa Pøngjǣrdenlarp
Ňɏssa Pøngjǣrdenlarp

Reputation: 38905

My preferred method is to (usually) store the controls names:

Dim panels as new List(Of String)

For n As integer = 0 to X
   Dim pnl As New Panel
   '... set values
   panels.Add(pnl.Name)
   Controls.Add(pnl)
Next n

To reference one:

Controls(panels(IndexofOneYouWant).Height = 100

Since you dynamically created the control, you could also be deleting them on occasion. In that case the List is not holding a reference to them when you go to remove one. If they remain once created, then a List(of Panel) is easier and better.

Upvotes: 0

Knaģis
Knaģis

Reputation: 21495

You can't do such variable access in VB.NET.

Instead of defining three variables, define an array or list

Dim panels as new List(Of Panel)
panels.Add(new Panel())
panels.Add(new Panel())

for x as integer = 0 to 1000
  Dim p as new Panel
  p.height = 100
  panels.Add(p)

  panels(x).width = 150
next

Upvotes: 0

Steven Doggart
Steven Doggart

Reputation: 43743

If this is a WinForm project, all of the controls are included in the form's Controls collection, which is accessible by name, like this:

For x As Integer = 0 to 1000
    Me.Controls("panel_" & i.ToString()).height = 100
Next

However, be aware that the form's Controls collection only contains the controls that are added directly to the form. If you have controls that are inside another container control, you will need to access them through that container's Controls property, for instance:

For x As Integer = 0 to 1000
    MyContainer.Controls("panel_" & i.ToString()).height = 100
Next

However, accessing controls by their string name may be something that you wish to avoid, since it can lead to unintended consequences down the road. As other's have suggested, it may be better to store the list of panels in a List(Of Panel) variable, which only contains the specific panel controls to which the resizing logic applies, like this:

Dim autoResizePanels As New List(Of Panel)({panel1, panel2, panel3})

Then, you can loop through them easily, like this:

For Each i As Panel In autoResizePanels 
    i.height = 100
Next

Upvotes: 3

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