datetime

/**
* WORKS WELL
*/

$intYear = 2010;

$arrDates = array();

$objStartTime   = DateTime::createFromFormat('d.m.Y', '1.1.' . $intYear);
$objStartTime->setTime(0,0,0);
$objEndTime = DateTime::createFromFormat('d.m.Y', '31.12.' . $intYear);

foreach(new DatePeriod($objStartTime, $objInterval, $objEndTime) as $objTime)
{
    $arrDates[] = $objTime->format('d.m.Y');
}

// -------------------------------------------------------------------------------------

/**
* DOESN'T WORK WELL - it skips months
*/

$intYear = 2010;

$arrDates = array();

$objStartTime   = DateTime::createFromFormat('d.m.Y', '1.1.' . $intYear);
$objStartTime->setTime(0,0,0);
$objEndTime = DateTime::createFromFormat('d.m.Y', '31.12.' . $intYear);

foreach(new DatePeriod($objStartTime, $objInterval, $objEndTime) as $objTime)
{
    echo $objTime->getTimestamp();
    $arrDates[] = $objTime->format('d.m.Y');
}