c# - File contents filtering -

i'm trying develop application take data datagrid , based on drop down menu choice return csv file selected client . code shown below , links previous question posted howeever still getting no values , need sort out i'm wondering if can either see i'm going wrong or else provide alternatives

    //master inventory export      private void exportclass_click(object sender, eventargs e)     {         stringbuilder str = new stringbuilder();         objsqlcommands2 = new sqlcommands("masterinventory", "clientname");         string strstring = str.tostring();         string filepath = txtsaveshareclass.text.tostring();         str.append("isin ,fundname,status,share ccy,benchmark,nav  freq,classcode,simulation,hedged,fundccy");          stringmanipulation sm = new stringmanipulation();          foreach (datarow dr in this.calcdataset.masterinventory)         {             foreach (object field in dr.itemarray)             {                 str.append(field.tostring() + ",");              }              str.replace(",", "\n", str.length - 1, 1);         }          try         {             system.io.file.writealltext(filepath, str.tostring());          }         catch (exception ex)         {             messagebox.show("write error :" + ex.message);         }          list<string[]> lsclientlist =  objstringmanipulation.parsecsv(filepath,cmbclientlist .text.tochararray());           foreach (string[] laclient in lsclientlist)         {             sm.parsecsv2(filepath, cmbclientlist.text.tochararray());             list<string[]> newfoo = lsclientlist.where(x =>  x.contains(cmbclientlist.text)).tolist();             list<string[]> results = sm.parsecsv2(filepath,    cmbclientlist.text.tochararray()).where(x => x.contains(cmbclientlist.text)).tolist();              //refreshs client table on display              system.io.file.writealltext(filepath, results.tostring());                      }          this.tableadapter.fill(this.calcdataset.masterinventory);          datagridview2.update();      } 

if of variables filling , results list contains data expect, problem writealltext call. have:

system.io.file.writealltext(filepath, results.tostring()); 

that not going produce output seem expect. give class name.

results list<string[]>. if want output csv, have enumerate it:

using (var outfile = new streamwriter(filepath)) {     foreach (var line in results)     {         stringbuilder sb = new stringbuilder();         foreach (var field in line)         {             sb.append(field + ",");         }         sb.length = sb.length -1;         outfile.writeline(sb.tostring());     } }