//First check to see that we are on a data row
if (e.Row.RowType == DataControlRowType.DataRow)
{
//now convert the text value to a double (use int32 for whole numbers)
if (Double.Parse(e.Row.Cells[2].Text) < Double.Parse(e.Row.Cells[1].Text))
{
//set the background to red
e.Row.Cells[5].Style.Add("background-color", "red");
//you can also access other properties such as font from here, as below
e.Row.Cells[5].Font.Bold = true;
}
}