Question

I want change background datagird cell base on value in c# windows application. for instance if cell value is 3 cell background color set to blue if cell value equal 2 cell background color change to red .

Answer 1

You can use CellFormatting event:

private void dataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    if (e.ColumnIndex == 1)
        {
            if ((int)e.Value == 3)
                e.CellStyle.BackColor = Color.Blue;
            if ((int)e.Value == 2)
                e.CellStyle.BackColor = Color.Red;
        }
}