Write a associative array to a CSV file.

array_2_csv.php

<?php

$arr = array();
$arr[0]['derp'] = 'hi';
$arr[0]['blerg'] = 'hey';

produceCSV('data.csv', $arr);

function produceCSV($file_name, $arr) {

  $has_header = false;

  foreach ($arr as $c) {

      $fp = fopen($file_name, 'a');

      if (!$has_header) {
        fputcsv($fp, array_keys($c));
        $has_header = true;
      }

      fputcsv($fp, $c);
      fclose($fp);

  }

}