PHP: get next 13 dates from date?

Question

I am trying to get an array of a date plus the next 13 dates to get a 14 day schedule starting from a given date.

here is my function:

$time = strtotime($s_row['schedule_start_date']); // 20091030
$day = 60*60*24;
for($i = 0; $i<14; $i++)
{
    $the_time = $time+($day*$i);
    $date = date('Y-m-d',$the_time);
    array_push($dates,$date);
}

But it seems to be repeating a date when the month switches over..

this is what I get:

2009-10-30|2009-10-31|2009-11-01|2009-11-01|2009-11-02|2009-11-03|2009-11-04|2009-11-05|2009-11-06|2009-11-07|2009-11-08|2009-11-09|2009-11-10|2009-11-11

Notice that 2009-11-01 is repeated. I cannot figure out why?

What am I doing wrong?

Thanks!!

Answer 1

You have the same date because of daylight saving time switch. It's not safe to add 24*60*60 seconds to find next day, because 2 days in the year have more/less seconds in them. When you switch from summer to winter time you are adding 1 hour to a day. So it'll be 25*60*60 seconds in that day, that's why it's not switched in your code.

You can do your calculation by mktime(). For example:

## calculate seconds from epoch start for tomorrow
$tomorrow_epoch = mktime(0, 0, 0, date("m"), date("d")+1, date("Y"));
## format result in the way you need
$tomorrow_date = date("M-d-Y", $tomorrow_epoch);

Or the full version for your code:

$dates = array();
$now_year = date("Y");
$now_month = date("m");
$now_day = date("d");
for($i = 0; $i < 14; $i++) {
    $next_day_epoch = mktime(0, 0, 0, $now_month, $now_day + $i, $now_year);
    array_push(
        $dates,
        date("Y-m-d", $next_day_epoch)
    );
}