void __fastcall TForm1::Button1Click(TObject *Sender)
{
  for (int nI = 0; nI < ComponentCount; nI  )
  {
    if ( Components[nI]->ClassNameIs("TPanel") )
      (dynamic_cast(Components[nI]))->Color = clRed; 
       // 可以在強制轉型之後，修改你所需要的屬性       
  }
}

 for (int i = 2; i <= 20; i  )
  {
   ((TPanel *)FindComponent("Panel" IntToStr(i)))->Color=clRed ;
  }