【Winform】Find out the changed rows in DataGridView

        DataTable dt = new DataTable();

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
            dt.Columns.Add("index", typeof(Int32));
            dt.Columns.Add("name", typeof(String));
            dt.Columns.Add("changed", typeof(Int32));
            dt.Rows.Add(new object[] { 1, "Chris" ,0});
            dt.Rows.Add(new object[] { 2, "Angie", 0 });
            dt.Rows.Add(new object[] { 3, "Tim", 0 });
            dt.Rows.Add(new object[] { 4, "Angela", 0 });
            dt.Rows.Add(new object[] { 5, "Bob", 0 });
            dt.Rows.Add(new object[] { 6, "Lory", 0 });
            dt.Rows.Add(new object[] { 7, "Michael", 0 });
            dt.Rows.Add(new object[] { 8, "Steve", 0 });
            dt.Rows.Add(new object[] { 9, "Nicky", 0 });
            dt.Rows.Add(new object[] { 10, "Dave", 0 });
            dt.DefaultView.Sort = "index DESC,name";

            //BindingSource bindSource = new BindingSource();
            //bindSource.DataSource = dt;
            
            dataGridView1.DataSource = dt;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            foreach (DataRow dr in dt.Rows)
            {
                if (dr["changed"].ToString() == "1")
                {
                    MessageBox.Show(dr["name"].ToString());
                }
            }

        }

        private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            DataGridViewRow row = this.dataGridView1.Rows[e.RowIndex];

            if (((DataRowView)row.DataBoundItem).Row.RowState != DataRowState.Unchanged)
            {
                //row.HeaderCell.Value = "***";
                row.Cells[2].Value = 1;
            }
        }

        private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
        {
            dataGridView1.Columns[2].Visible = false;
        }