PHP 生成 CSV 文件

<?php$csv = "";foreach ($data as $row) {  $csv .= join(",", $row) . "n";}echo $csv;?> <?php function toCSV(array $data, array $colHeaders = array(), $asString = false) {     $stream = ($asString)      ? fopen("php://temp/maxmemory", "w+")      : fopen("php://output", "w");      if (!empty($colHeaders)) {        fputcsv($stream, $colHeaders);     }     foreach ($data as $record) {        fputcsv($stream, $record);    }     if ($asString) {        rewind($stream);         $returnVal = stream_get_contents($stream);         fclose($stream);         return $returnVal;     }    else {        fclose($stream);     } }