TStringList的IndexOf有关问题

TStringList的IndexOf问题？
void __fastcall TForm1::exitClick(TObject *Sender)
{
  AnsiString sSql;
TADOQuery* pADOQuery = new TADOQuery(NULL);
pADOQuery->Connection=this->ADOConnection1;
sSql += "select 权限代码 from am_purview where 用户代号 ='";
sSql += daima->Text + "'";
pADOQuery->SQL->Add(sSql);
pADOQuery->Open();
TStringList* plst=new TStringList();
while(!pADOQuery->Eof)
{
plst->Add(pADOQuery->FieldByName("权限代码")->AsString.Trim());
Memo1->Lines->Add(pADOQuery->FieldByName("权限代码")->AsString.Trim());
  //Memo1显示值已经取出来了。。如exit等。。。 数据类型为char
pADOQuery->Next();
}
if(plst->IndexOf(exit->Name)<=0)
{
MessageBox(NULL,"失败","系统提示",MB_OK);
}
else
{
MessageBox(NULL,"恭喜","系统提示",MB_OK);
}
delete pADOQuery;
delete plst;
}

可是提示失败也就是条件为真。下面代码通过，条件为否。所以我判断是红色部分出了问题。肯请大家指点指点。。
void __fastcall TForm1::exitClick(TObject *Sender)
{
TStringList* plst=new TStringList();
  plst->Add("open");
  plst->Add("exit");
  if(plst->IndexOf(exit->Name)<=0)
  {
  MessageBox(NULL,"失败","提示",MB_OK);
  }
else
{
MessageBox(NULL,"恭喜","提示",MB_OK);
}
  delete plst;
}


[解决办法]
IndexOf的返回值为0表示有效，所以那个判断条件 应该是 < 0即可，而不是 <= 0
[解决办法]

C/C++ code

void __fastcall TForm1::exitClick(TObject *Sender){TStringList* plst=new TStringList();  plst->Add("open");  plst->Add("exit");  if(！plst->IndexOf(exit->Name))  {  MessageBox(NULL,"失败","提示",MB_OK);  }else{MessageBox(NULL,"恭喜","提示",MB_OK);}  delete plst;