Question: I have the below line of codes 

```
$day1 = new Zend_Date('2010-03-01', 'YYYY-mm-dd');
$day2 = new Zend_Date('2010-03-05', 'YYYY-mm-dd');
$dateDiff = $day2->getDate()->get(Zend_Date::TIMESTAMP) - $day1->getDate()->get(Zend_Date::TIMESTAMP);
$days = floor((($dateDiff / 60) / 60) / 24);
return  $days;  

```

this will return 4

But if gave 

```
$day1 = new Zend_Date('2010-02-28', 'YYYY-mm-dd');
$day2 = new Zend_Date('2010-03-01', 'YYYY-mm-dd');
$dateDiff = $day2->getDate()->get(Zend_Date::TIMESTAMP) - $day1->getDate()->get(Zend_Date::TIMESTAMP);
$days = floor((($dateDiff / 60) / 60) / 24);
return  $days; 

```

it will return -27 .. how will i get right answer

Answer: 
```
$firstDay = new Zend_Date('2010-02-28', 'YYYY-MM-dd');
$lastDay = new Zend_Date('2010-03-01', 'YYYY-MM-dd');
$diff = $lastDay->sub($firstDay)->toValue();
$days = ceil($diff/60/60/24) +1;

```

return $days;

this gives the right answer
I believe the problem is in your part string. Try **YYYY-MM-dd** instead.

```
$day1 = new Zend_Date('2010-02-28', 'YYYY-MM-dd');
$day2 = new Zend_Date('2010-03-01', 'YYYY-MM-dd');
echo $day2->sub($day1)->toString(Zend_Date::DAY);

```