DataTable People = new DataTable("People");

            //Create the Columns in the DataTable

            DataColumn c0 = new DataColumn("Name");

            DataColumn c1 = new DataColumn("Phone");

            DataColumn c2 = new DataColumn("Address");

            //Add the Created Columns to the Datatable

            People.Columns.Add(c0);

            People.Columns.Add(c1);

            People.Columns.Add(c2);

            //Create 3 rows

            DataRow row, row1, row2;

            row = People.NewRow();

            row["Name"] = "Fred";

            row["Phone"] = "555-1234";

            row["Address"] = "Hollywood CA";

            row1 = People.NewRow();

            row1["Name"] = "Bob";

            row1["Phone"] = "555-4567";

            row1["Address"] = "Washington DC";

            row2 = People.NewRow();

            row2["Name"] = "Sam";

            row2["Phone"] = "555-7890";

            row2["Address"] = "Milwaukee WI";

            //Add 3 rows to table

            People.Rows.Add(row);

            People.Rows.Add(row1);

            People.Rows.Add(row2);

            dataGridView1.DataSource = People;
            if (string.IsNullOrEmpty(dataGridView1.Rows[dataGridView1.CurrentCell.RowIndex].Cells[1].Value as string))
            {
                MessageBox.Show("Il campo è vuoto");
                return;
            }
            else
            {
                MessageBox.Show("Il campo è pieno");
                return;
            }

   if (string.IsNullOrEmpty(dataGridView1.Rows[dataGridView1.CurrentCell.RowIndex].Cells[1].Value as string))
            {
                MessageBox.Show("Il campo è vuoto");
                return;
            }

  var myValue = DataGridView.CurrentCell.Value as string;
            if (string.IsNullOrWhiteSpace(myValue as string))
            {
                MessageBox.Show("La cella selezionata è vuota");
            }
            else
            {
                MessageBox.Show(myValue as string);
            }

  var contatoreNumeroColonna = 0;
            foreach (DataGridViewTextBoxCell cell in DataGridView.Rows[DataGridView.CurrentCell.RowIndex].Cells)
            {
                if (string.IsNullOrWhiteSpace(cell.Value as string))
                {
                    MessageBox.Show($"La riga selezionata ha il campo {DataGridView.Columns[contatoreNumeroColonna].HeaderText} vuoto");
                    return;
                }
               
                contatoreNumeroColonna++;
            }
         
            MessageBox.Show("La riga selezionata ha tutti i campi compilati");