Subtracting Dates

programming
1

I want to go 7 days back from a certain date but when I do so the days go into negative?


<?php
$date = "09/01/09";
$date = strtotime( (string) $date );
$day = date('d', $date);
$month = date('F', $date);
$year = date('Y', $date);
for ($i = 1; $i <= 7; $i++) {
    echo "$month, $day, $year<br />";
    $day--;
}
?>

output


September, 01, 2009
September, 0, 2009
September, -1, 2009
September, -2, 2009
September, -3, 2009
September, -4, 2009
September, -5, 2009