private void frmAddCustomer_Load(object sender, EventArgs e) { List <Button> rooms = new List <Button> { btn101, btn102, btn103, btn104, btn201, btn202, btn203, btn204, btn301, btn302, btn303, btn304, btn401, btn402, btn403, btn404, btn501, btn502, btn503, btn504 }; var list = bo.GetListInHostel(); foreach (var item in list) { foreach (var room in rooms) { if (room.Text == item.RoomNumber.ToString()) { room.BackColor = Color.Red; room.Enabled = false; } } } }