Bijan
This one is not that exact
I'm not sure what you mean by not exact. The code above deals with seconds so by dividing by 60 60 24 ( 60 seconds in a minute 60 minutes in an hour 24 hours in a day) or 86400 (which is how many seconds are in one day, be it a leap year day or any other)
By getting the difference in seconds between days and dividing by the # of seconds in a day it gives you how many days between the two. Which would not make any difference whether it was a leap year or not.