public DataTable GetDataFromExcel() 
          { 
              Excel.Application xlApp; 
              Excel.Workbook xlWorkBook; 
              Excel.Worksheet xlWorkSheet; 
              Excel.Range range; 
   
              System.Data.DataTable dt = new System.Data.DataTable(); 
   
   
              xlApp = new Excel.Application(); 
              xlWorkBook = xlApp.Workbooks.Open(Application.StartupPath + "\\maliyet.xls", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0); 
              xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1); 
   
              range = xlWorkSheet.UsedRange; 
   
              dt.Columns.Add("ESKI_STOK_KODU"); 
              dt.Columns.Add("STOK_KODU"); 
              dt.Columns.Add("STOK_ADI"); 
   
              dt.Columns.Add("Genel Gider"); 
              dt.Columns.Add("Tölerans"); 
              dt.Columns.Add("Kâr"); 
              dt.Columns.Add("Min Satış"); 
   
              dt.Columns.Add("YUKSEK_FIYAT"); 
              dt.Columns.Add("DUSUK_FIYAT"); 
              dt.Columns.Add("ORT_FIYAT"); 
              dt.Columns.Add("MALIYET"); 
              dt.Columns.Add("İstenilen Maliyet"); 
   
              DataRow bos = dt.NewRow(); 
              dt.Rows.Add(bos); 
   
   
              string satir = xlWorkSheet.Rows[4].Cells[1].Value; 
              string[] data = st.StringParser(new string[] { " " }, satir); 
   
              //datayı excelden doldu 
              for (int i = 5; i <= range.Rows.Count - 2; i++) 
              { 
   
                  string excSatir = xlWorkSheet.Rows[i].Cells[1].Value; 
                  DataRow dr = dt.NewRow(); 
                  int startPoint = 0; 
                  int okunacakBoy = 0; 
                  for (int k = 0; k < data.Length; k++) 
                  { 
   
                      okunacakBoy = data[k].Length - 1; 
                      if (k <= 2) 
                      { 
                          dr[k] = excSatir.Substring(startPoint, okunacakBoy).Trim().ToString(); 
                          if (excSatir.Substring(startPoint, okunacakBoy).Trim().Substring(0, 1).Contains(".")) 
                          { 
                              dr[k] = "0." + excSatir.Substring(startPoint, okunacakBoy).Trim().Remove(0, 1).ToString().Replace(".", ",").ToString(); 
                          } 
                      } 
                      else if (k >= 2 && k <= 7) 
                      { 
                          dr[k + 4] = excSatir.Substring(startPoint, okunacakBoy).Trim().ToString(); 
                          if (excSatir.Substring(startPoint, okunacakBoy).Trim().Substring(0, 1).Contains(".")) 
                          { 
                              dr[k + 4] = "0." + excSatir.Substring(startPoint, okunacakBoy).Trim().Remove(0, 1).Replace(".", ",").ToString(); 
                          } 
                      } 
   
   
   
   
                      startPoint += data[k].Length - 1; 
   
   
                  } 
   
                  dt.Rows.Add(dr); 
              } 
   
              foreach (DataRow item in dt.Rows) 
              { 
                  string r = item["İstenilen Maliyet"].ToString(); 
                  item["İstenilen Maliyet"] = r.Replace(".", ","); 
   
                  r = item["YUKSEK_FIYAT"].ToString(); 
                  item["YUKSEK_FIYAT"] = r.Replace(".", ","); 
   
                  r = item["DUSUK_FIYAT"].ToString(); 
                  item["DUSUK_FIYAT"] = r.Replace(".", ","); 
   
                  r = item["ORT_FIYAT"].ToString(); 
                  item["ORT_FIYAT"] = r.Replace(".", ","); 
   
                  r = item["MALIYET"].ToString(); 
                  item["MALIYET"] = r.Replace(".", ","); 
   
              } 
   
   
              xlWorkBook.Close(true, null, null); 
              xlApp.Quit(); 
              releaseObject(xlWorkSheet); 
              releaseObject(xlWorkBook); 
              releaseObject(xlApp); 
   
   
              return dt; 
          }

private void releaseObject(object obj) 
          { 
              try 
              { 
                  System.Runtime.InteropServices.Marshal.ReleaseComObject(obj); 
                  obj = null; 
              } 
              catch (Exception ex) 
              { 
                  obj = null; 
                  MessageBox.Show("Unable to release the Object " + ex.ToString()); 
              } 
              finally 
              { 
                  GC.Collect(); 
              } 
          }