Looping through Controls in VB.NET

Question

I am creating a chess program. And it is composed of sixty four picture boxes with alternating black and white background colours.
I have named them pba1,

Answer 1

Generating controls at design time via the Forms Designer only makes sense for layouts which benefit from the forms designer.

In your case, you just have 64 uniform boxes in 8 rows of 8. Don’t use the Forms Designer for this, create the controls at runtime, and don’t give them names like pba1, just put them into an appropriate data structure (such as an 8x8 array):

Private chessFields As PictureBox(8, 8)

' In Form_Load:
For i = 0 To 7
    For j = 0 To 7
        chessFields(i, j) = New PictureBox
        ' Set size, position … then, finally,
        Controls.Add(chessFields(i, j))
    Next
Next

That way, you can access the fields in an orderly fashion without having to go via the Form.Controls collection.

Answer 2

This is fairly simple and it may be resource heavy, but it works. I have a form with 36 CheckBoxes. This takes advantage of the fact that when you copy a checkbox it just increases the number of the name. I ended up with 36 checkboxes named CheckBox1 thru Checkbox36. The Function returns a checkbox, which may be used to set or read any property.

Private Function GetCheckBox(ByVal Index As Integer) As CheckBox
    Dim CKBox As checkbox
    For Each cntrl As Control In Me.Controls
        If TypeOf cntrl Is CheckBox Then
            CKBox = cntrl
            If CKBox.Name = "CheckBox" & Index Then
                Exit For
            End If
        End If
    Next
    Return ckbox
End Function

Answer 3

Loop through the PictureBox's in your ControlCollection and test for BackColor. I used the Form's ControlCollection, if they are in some other type of container control use that.

For Each cntrl As Control In Me.Controls
    If TypeOf cntrl Is PictureBox Then
        If cntrl.BackColor = Color.Black Then
            'Do Something
        End If
    End If
Next

---

Base on the additional information that you gave in your answer, the reason your example is not working is that the Controls Name is a String and you are comparing it to the PictureBox Control not the Name of the Control.

You can try using the Tag Property instead of the Name of the Control, it will be cleaner and easier to read. I just put a 1 in the PictureBox's Tag Property for Black and a 0 for White.

Private Sub OriginalColour()               
    For Each cntrl As Control In Me.Controls
        Dim result As Integer
        If TypeOf cntrl Is PictureBox Then
            If Integer.TryParse(cntrl.Tag.ToString, result) Then
                If result = 1 Then
                    cntrl.BackColor = Color.Gray
                Else
                    cntrl.BackColor = Color.White
                End If
            End If

        End If
    Next
End Sub

Answer 4

Put all the pictureboxes in an 8x8 tableLayoutPanel (also useful for scaling etc). Then

    For Each pb As PictureBox In TableLayoutPanel1.Controls
        Dim col As Integer = TableLayoutPanel1.GetCellPosition(pb).Column
        Dim row As Integer = TableLayoutPanel1.GetCellPosition(pb).Row
        If col Mod 2 = 0 Xor row Mod 2 = 0 Then
            pb.BackColor = Color.Black
        Else
            pb.BackColor = Color.White
        End If
    Next

Of course you could also use an array of the squares if you have that available.

This will not affect the events (pba1.click etc).