'---How to get the index of the currently selected row


If InvoicesDataGridView.Rows.Count > 0 Then
    Dim rowIndex As Integer = _
        InvoicesDataGridView.CurrentCell.RowIndex
End If


'---How to get the value of the first cell in the selected row

Dim row As DataGridViewRow = _
    InvoicesDataGridView.Rows(rowIndex)

Dim cell As DataGridViewCell = row.Cells(0)

Dim invoiceID As Integer = CInt(cell.Value)



'---How to set the value of the first cell in the selected row
Dim invoiceID As Integer = 10
Dim row As DataGridViewRow = _
    InvoicesDataGridView.Rows(rowIndex)
	row.Cells(0).Value = invoiceID




'---How to loop through all rows in the grid
Dim grandTotal As Decimal = 0
For Each row As DataGridViewRow _
    In InvoicesDataGridView.Rows
        Dim cell As DataGridViewCell = row.Cells(3)
        Dim invoiceTotal As Decimal = CDec(cell.Value)
        grandTotal += invoiceTotal
Next


'---How to refresh the grid
InvoicesDataGridView.Refresh()



'---A method that handles the CellDoubleClick event
Private Sub InvoicesDataGridView_CellDoubleClick( _
        ByVal sender As System.Object, _
        ByVal e As _
            System.Windows.Forms.DataGridViewCellEventArgs) _
        Handles InvoicesDataGridView.CellDoubleClick
    Dim rowIndex As Integer = e.RowIndex
    Me.DisplayLineItems(rowIndex)
End Sub


'---How to delete a row
InvoicesDataGridView.Rows.RemoveAt(rowIndex)