PHP가 csv 파일을 생성할 때 주의할 점

header("Content-type: application/octet-stream");
header("Content-Disposition: attachment; filename=vote".time().".csv; charset=utf-8");

若是utf-8的话，则必须先输出BOM信息，切记：

echo "/xEF/xBB/xBF".$output;