private void dataGridView_C_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
        {
            if (e != null)
            {
                if (dataGridView_C.Rows[e.RowIndex].Cells["xx"].Value.ToString() != "1")
                {
                    dataGridView_C.Rows[e.RowIndex].Cells["xxx"].Style.ForeColor = Color.Red;
                }
                else
                {
                    dataGridView_C.Rows[e.RowIndex].Cells["xxx"].Style.ForeColor = Color.Black;
                }
            }
        } 开始运行正常,当滚动条移动时,发现会产生: “e.RowIndex”引发了“System.NullReferenceException”类型的异常 ,跟踪程序发现 e 的所有属性都为空,但 e 不为空 ,在这里如何控制这个异常的发生