使用PHP按类型将$ _POST大写到CSV文件中

i'm trying to put a large Form submited into rows and columns on a CSV file.
All input name's ends like
"something_dados", "something_id_desc", "something_pergunta", "something_resposta", "something_data", "something_obs"

my goal is:

("Dados"),
("ID Descrição"),
("Pergunta, Resposta, Data"),
("Pergunta, Resposta, Data"),
...
("Pergunta, Resposta, Data"),
("Obs");

$dadosCSV = fopen(dirname(__FILE__).'/csv/data_'.$_POST['razao_dados'].'.csv' , 'w');

foreach($_POST as $key => $value){
    if(strpos($key, '_dados')){
        $dados_posto = $value;
        fputcsv($dadosCSV, $dados_posto);
    }
    if(strpos($key, '_id_desc')){
        $id_desc = $value;
        fputcsv($dadosCSV, $id_desc);
    }
    if(strpos($key, '_pergunta')){
        $pergunta[] = $value;
    }
    if(strpos($key, '_resposta')){
        $resposta[] = $value;
    }
    if(strpos($key, '_date')){
        $data[] = $value;
    }
    if(strpos($key, '_obs')){
        $obs = $value;
        fputcsv($dadosCSV, $obs);
    }
}
$arr = array($pergunta, $resposta, $data);

fclose($dadosCSV);