PHP exports csv file, can export leading 0 instance code

//Export csv format file $data data $title_arr title $file_name file namefunction exportCsv($data,$title_arr,$file_name=''){
  ini_set("max_execution_time", "3600");

  $csv_data = '';
  /** Title */
  $nums = count($title_arr);

  for ($i = 0; $i < $nums - 1; ++$i) {
    $csv_data .= '"' . $title_arr[$i] . '",';
  }
  if ($nums > 0) {
    $csv_data .= '"' . $title_arr[$nums - 1] . "\"\r\n";
  }

  foreach ($data as $k => $row) {
    foreach ($row as $key => $r){

      $row[$key] = str_replace("\"", "\"\"", $r);

      $csv_data .= "\"\t" . $row[$key] . '",';
    }

    $csv_data .= '"' . $row[$nums - 1] . "\"\r\n";
    unset($data[$k]);
  }
  $csv_data = mb_convert_encoding($csv_data, "cp936", "UTF-8");
  $file_name = empty($file_name) ? date('Y-m-d-H-i-s', time()) : $file_name;
  if (strpos($_SERVER['HTTP_USER_AGENT'], "MSIE")) { // Solve the bug in IE browser outputting Chinese name garbled code    $file_name = urlencode($file_name);
    $file_name = str_replace('+', '%20', $file_name);
  }
  $file_name = $file_name . '.csv';
  header('Content-Type: application/download');
  header("Content-type:text/csv;");
  header("Content-Disposition:attachment;filename=" . $file_name);
  header('Cache-Control:must-revalidate,post-check=0,pre-check=0');
  header('Expires:0');
  header('Pragma:public');
  echo $csv_data;
  exit();
}