PHP: Generate range of dates

range_of_dates.php

<?php

function _date_range($first, $last, $step = '+1 day', $format = 'Y-m-d') {
  $dates = array();
  $current = strtotime($first);
  $last = strtotime($last);

  while ($current <= $last) {
    $dates[] = date($format, $current);
    $current = strtotime($step, $current);
  }

  return $dates;
}

var_dump(_date_range('1 month ago', 'now'));