title: Handle empty cells in DataGridView
body: <p>I want to write a condition for when some cells of DataGridView are null or empty.
  For example if cells[1] isn't null or empty , a method must be run and ...
  I wrote it in some way , but some of them didn't work, and one of them work but its not good solution for my problem.As you now ,empty and null are different in DataGridView.
  Additionally , My DataGridView has not been bound to database.
  How can i do that in best way?
  Regards. </p>