How to get all days and date for a given month?

This is to get all days and date for choosen month. Just follow the code to display all the dates for a month.

$month = "07";
$year = "2018";

$startDate = "01-".$month."-".$year;
$startTime  = strtotime($startDate);

$endTime = strtotime("+1 month", $startTime);

for($i=$startTime; $i<$endTime; $i+=86400)
{
   $list[] = date('Y-m-d-D', $i);
}

print_r($list);