private void btnBillSearch_Click(object sender, EventArgs e) { string searchString = txtBillSearchString.Text; DateTime?fromDate = dtpBillSearchFromDate.Checked ? (DateTime?)dtpBillSearchFromDate.Value : null; DateTime?toDate = dtpBillSearchToDate.Checked ? (DateTime?)dtpBillSearchToDate.Value : null; decimal fromTotal = nmrBillFromTotal.Value; decimal toTotal = nmrBillToTotal.Value; List <Bill> bills = billBUS.Search(searchString, fromDate, toDate, fromTotal, toTotal); ShowBills(bills); }