Add missing dates to an array

Question

I have the following array:

Array ( [2010-10-30] => 1 [2010-11-11] => 1 [2010-11-13] => 11 )

I am trying to fill in the array with all the missing dates between the first and last elements. I was attempting using the following but got nowhere:

foreach($users_by_date as $key => $value){
    $real_next_day = date($key, time()+86400);
    $array_next_day = key(next($users_by_date));
    if($real_next_day != $array_next_day){
      $users_by_date[$real_next_day] = $value;
    }
}

Answer 1

The DateTime, DateInterval and DatePeriod classes can really help out here.

$begin=date_create('2010-10-30');
$end=date_create('2010-11-13');
$i = new DateInterval('P1D');
$period=new DatePeriod($begin,$i,$end);

foreach ($period as $d){
  $day=$d->format('Y-m-d');
  $usercount= isset($users_by_date[$day]) ? $users_by_date[$day] :0;
  echo "$day $usercount"; 
}

Answer 2

I have been waiting for a chance to try out DateTime and DateInterval objects in PHP 5.3, your question was the perfect opportunity to do just that. Note that this code will not work with PHP versions earlier than 5.3

<?php
$dates = array('2010-10-30' => 1, '2010-11-01' => 1, '2010-11-13' => 1);

// get start and end out of array
reset($dates);
$start = new DateTime(key($dates));

end($dates);
$end   = new DateTime(key($dates));

foreach (new DatePeriod($start, new DateInterval('P1D'), $end) as $date) {
    $dateKey = $date->format('Y-m-d'); // get properly formatted date out of DateTime object
    if (!isset($dates[$dateKey])) {
        $dates[$dateKey] = 1;
    }
}

print_r($dates);