Can I use variables to control which PictureBox I am using? - vb.net

Question

Is there a way that I can use a variable to control which PictureBox I am using in Visual Basic?
I.e.:
CurrentNumber = 1
PictureBox(CurrentNumber).backcolour = backcolour

Answer 1

You can use the Me.Controls(String) indexer. It lets you specify the name (as a string) of the control you want to access, thus you can dynamically access a picture box by concatenating the string "PictureBox" with a number.
Dim TargetPictureBox As PictureBox = TryCast(Me.Controls("PictureBox" & CurrentNumber), PictureBox)
'Verifying that the control exists and that it was indeed a PictureBox.
If TargetPictureBox IsNot Nothing Then
TargetPictureBox.BackColor = Color.Red
End If
Alternatively, to save processing power by avoiding looping through the entire control collection every time you can call the OfType() extension on Me.Controls, storing the result in an array sorted by the controls' names. That way it'd only have to iterate the control collection once.
'Class level - outside any methods (subs or functions).
Dim PictureBoxes As PictureBox() = Nothing
'Doesn't necessarily have to be done in a button, it's just an example.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If PictureBoxes Is Nothing Then
PictureBoxes = Me.Controls.OfType(Of PictureBox).OrderBy(Function(p As PictureBox) p.Name).ToArray()
End If
'NOTE: CurrentNumber - 1 is necessary when using an array!
PictureBoxes(CurrentNumber - 1).BackColor = Color.Red
End Sub
NOTE: This solution will only work properly if all your picture boxes are named "PictureBox1", "PictureBox2", etc. If you suddenly skip a number ("PictureBox3", "PictureBox5", "PictureBox6") then PictureBoxes(CurrentNumber - 1) for CurrentNumber = 5 would return PictureBox6 rather than PictureBox5.

Answer 2

What you really should do is create a PictureBox() and use that to reference your picture boxes via an index.
The best way to build your array is to create a method that builds the array from the references created by the designer. This lets you continue to use the designer to create your controls and it makes your code check for deleted controls at design-time. Using Me.Controls(...) suffers from run-time errors if controls you are looking for have been deleted.
Here's the code you need:
Private _PictureBoxes As PictureBox() = Nothing
Sub AssignPictureBoxesArray
_PictureBoxes = {PictureBox1, PictureBox2, PictureBox3}
End Sub
Then you access them like this:
Sub SomeMethod
Dim CurrentNumber = 1
Dim PictureBox = _PictureBoxes(CurrentNumber - 1)
PictureBox.BackColor = System.Drawing.Color.Red
End Sub