Question

I have a DataGridView which contains a DataGridViewColumn and also a button. When I click the button I want to check if all checkboxes in the datagridview are checked or not.

I use the following code but it is not working:

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    For i As Integer = 0 To DataGridView1.Rows.Count - 1
        Dim CheckBox As DataGridViewCheckBoxCell = DirectCast(DataGridView1.Rows(i).Cells(0), DataGridViewCheckBoxCell)
        If Not CheckBox.Value = Not CheckBox.Value Then
            MsgBox("True")
        End If
    Next
End Sub

Answer 1

I can’t really tell what your logic is supposed to be doing with this line:

If Not CheckBox.Value = Not CheckBox.Value Then

It looks like you are saying, “if Not Value = Not Value” ???

Try this:

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
  For i As Integer = 0 To DataGridView1.Rows.Count - 1
    'Dim CheckBox As DataGridViewCheckBoxCell = DirectCast(DataGridView1.Rows(i).Cells(0), DataGridViewCheckBoxCell)
    'If Not CheckBox.Value = Not CheckBox.Value Then
    '  MsgBox("True")
    'End If
    Dim obj As Object = DataGridView1.Rows(i).Cells(0)
    If (Not obj Is Nothing) Then
      Dim checkBox1 As DataGridViewCheckBoxCell = DirectCast(obj, DataGridViewCheckBoxCell)
      Dim objValue As Object = checkBox1.Value
      If (Not objValue Is Nothing) Then
        Dim checked As Boolean = DirectCast(objValue, Boolean)
        If (checked) Then
          MsgBox("True")
        End If
      End If
    End If
  Next
End Sub