Microsoft Excel mangles Diacritics in .csv files?

Question

I am programmatically exporting data (using PHP 5.2) into a .csv test file.
Example data: Numéro 1 (note the accented e). The data is utf-8 (

Answer 1

Below is the PHP code I use in my project when sending Microsoft Excel to user:

  /**
   * Export an array as downladable Excel CSV
   * @param array   $header
   * @param array   $data
   * @param string  $filename
   */
  function toCSV($header, $data, $filename) {
    $sep  = "\t";
    $eol  = "\n";
    $csv  =  count($header) ? '"'. implode('"'.$sep.'"', $header).'"'.$eol : '';
    foreach($data as $line) {
      $csv .= '"'. implode('"'.$sep.'"', $line).'"'.$eol;
    }
    $encoded_csv = mb_convert_encoding($csv, 'UTF-16LE', 'UTF-8');
    header('Content-Description: File Transfer');
    header('Content-Type: application/vnd.ms-excel');
    header('Content-Disposition: attachment; filename="'.$filename.'.csv"');
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    header('Content-Length: '. strlen($encoded_csv));
    echo chr(255) . chr(254) . $encoded_csv;
    exit;
  }

UPDATED: Filename improvement and BUG fix correct length calculation. Thanks to TRiG and @ivanhoe011