Datagridview - Input string was not in a correct format

[gbhs]

Hi
I have a datagrid with 2 columns (Scores(Int) index 0 and Comment(nchar) index 1)
Comment columnvalue depends on score value.

This code works well in my cellvaluechanged event

If e.ColumnIndex = 0 Then
If Not IsDBNull(Me.dgvStudDisc.Rows(e.RowIndex).Cells(e.ColumnIndex).Value) Then
If Me.dgvStudDisc.Rows(e.RowIndex).Cells(e.ColumnIndex).Value >= 0 And
Me.dgvStudDisc.Rows(e.RowIndex).Cells(e.ColumnIndex).Value <= 5 Then
Me.dgvStudDisc.Rows(e.RowIndex).Cells(1).Value = "Very Poor"
Else
Me.dgvStudDisc.Rows(e.RowIndex).Cells(1).Value = DBNull.Value
End If
End If
End if

PROBLEM: when I enter a value in score column and want to delete it I get the above exception.
Can someone help me modify the code to handle this problem?
gbhs

 

[jmcilhinney]

Does that first column allow nulls?

By the way, don't keep using expressions like 'Me.dgvStudDisc.Rows(e.RowIndex)' and 'Me.dgvStudDisc.Rows(e.RowIndex).Cells(e.ColumnIndex).Value' over and over. Good practice dictates that you evaluate those expressions once only and assign their value to a variable and use that repeatedly, e.g.

Dim row = Me.dgvStudDisc.Rows(e.RowIndex)
Dim currentCellValue = row.Cells(e.ColumnInde x).Value
Dim nextCell = row.Cells(1)

If currentCellValue Is DBNull.Value Then
    nextCell.Value = DBNull.Value
Else
    Select Case CInt(currentCellValue)
        Case < 0
            '...
        Case < 6
            nextCell.Value = "Very Poor"
        Case Else
            '...
    End Select
End If

I assume that your data is bound too, so you might even do away with that code altogether and instead set the Expression property of the second DataColumn.