public function excel(){ 
      $dateHelper = Loader::helper('date');
 
      $this->pageSize=0;
      $this->loadSurveyResponses();
      $textHelper = Loader::helper('text');
 
      $questionSet=$this->get('questionSet');
      $answerSets=$this->get('answerSets');
      $questions=$this->get('questions');   
      $surveys=$this->get('surveys');    
 
      $fileName=$textHelper->filterNonAlphaNum($surveys[$questionSet]['surveyName']);
      ini_set("memory_limit", "256M");
      header("Content-Type: application/vnd.ms-excel");
      header("Cache-control: private");
      header("Pragma: public");
      $date = date('Ymd');
      header("Content-Disposition: inline; filename=".$fileName."_form_data_{$date}.xls"); 
      header("Content-Title: ".$surveys[$questionSet]['surveyName']." Form Data Output - Run on {$date}");      
      echo "<table>\r\n";
      $hasCBRow = false;
      foreach($questions as $questionId=>$question){ 
            if ($question['inputType'] == 'checkboxlist') {
            $hasCBRow = true;
         }
      }
 
      echo "<tr>";
      echo "\t\t<td ";
      if ($hasCBRow) {
         echo "rowspan=\"2\" valign='bottom'";
      }
      echo "><b>Submitted Date</b></td>\r\n";
 
      foreach($questions as $questionId=>$question){ 
            if ($question['inputType'] == 'checkboxlist')
            {
                $options = explode('%%', $question['options']);
             echo "\t\t".'<td colspan="'.count($options).'"><b>'."\r\n";
            }
            else
            {
             echo "\t\t<td ";
             if ($hasCBRow) {
                echo "rowspan=\"2\" valign='bottom'>";
             }
             echo "<b>\r\n";
            }
         echo "\t\t\t".$questions[$questionId]['question']."\r\n";
         echo "\t\t</b></td>\r\n";         
      }   
      echo "</tr>";
 
      // checkbox row
      if ($hasCBRow) {
         echo "<tr>";
         foreach($questions as $questionId=>$question){ 
            if ($question['inputType'] == 'checkboxlist')
            {
               $options = explode('%%', $question['options']);
               foreach($options as $opt) {
                  echo "<td><b>{$opt}</b></td>";
               }
            }
         }
         echo "</tr>";
      }
      $total = count($answerSets);
      $sliceAmt = 10000;
      for($slicePos = 0; $slicePos < $total; $slicePos += $sliceAmt) {
 
         $slice = array_slice($answerSets, $slicePos, $sliceAmt);
         set_time_limit(10);
 
         foreach($slice as $answerSetId=>$answerSet){ 
            $questionNumber=0;
            $numQuestionsToShow=2;
            echo "\t<tr>\r\n";
            echo "\t\t<td>". $dateHelper->getSystemDateTime($answerSet['created'])."</td>\r\n";
            foreach($questions as $questionId=>$question){ 
               $questionNumber++;
               if ($question['inputType'] == 'checkboxlist'){
                  $options = explode('%%', $question['options']);
                  $subanswers = explode(',', $answerSet['answers'][$questionId]['answer']);
                  for ($i = 1; $i <= count($options); $i++)
                  {
                     echo "\t\t<td align='center'>\r\n";
                     if (in_array(trim($options[$i-1]), $subanswers)) {
                        // echo "\t\t\t".$options[$i-1]."\r\n";
                        echo "x";
                     } else {
                        echo "\t\t\t \r\n";
                     }
                     echo "\t\t</td>\r\n";
                  }
 
               }elseif($question['inputType']=='fileupload'){ 
                  echo "\t\t<td>\r\n";
                  $fID=intval($answerSet['answers'][$questionId]['answer']);
                  $file=File::getByID($fID);
                  if($fID && $file){
                     $fileVersion=$file->getApprovedVersion();
                     echo "\t\t\t".'<a href="'. $fileVersion->getDownloadURL() .'">'.$fileVersion->getFileName().'</a>'."\r\n";
                  }else{
                     echo "\t\t\t".t('File not found')."\r\n";
                  }    
                  echo "\t\t</td>\r\n";      
               }else{               
                  echo "\t\t<td>\r\n";
                  echo "\t\t\t".$answerSet['answers'][$questionId]['answer'].$answerSet['answers'][$questionId]['answerLong']."\r\n";               
                  echo "\t\t</td>\r\n";
               }
            }
            echo "\t</tr>\r\n";
         }
         unset($slice);
      }
      echo "</table>\r\n";
 
      die;
   }