for (int i = 0; i < GridView1.Rows.Count; i++)
{
if (GridView1.Rows.Count % 2 == 0)
{
e.Row.Cells[0].BackColor = System.Drawing.Color.Green;
e.Row.Cells[1].BackColor = System.Drawing.Color.Green;
}
else
{
e.Row.Cells[0].BackColor = System.Drawing.Color.Red;
e.Row.Cells[0].BackColor = System.Drawing.Color.Red;
}
}