Number of years passed - Consider leap year

Question

In our HR system, we want to calculate the number of years the employee has served the company.

What we have is the joining date in TIMESTAMP column.

What I am doing is:

$timeNow = time(); // current time
$joinDate = strtotime($users->fields['date_of_joining']); // from database
$servicePeriod = $timeNow - $joinDate; // in seconds
$servicePeriod = $servicePeriod / 31570560; // in years

But will this take the leap years into consideration? If an employee joined in Feb 27 of a leap year and if we check the status next year by March 1, he should still be reported as served for 1 year and not 1 year and 1 day.

Any ideas on this? Thanks.

Answer 1

Your method seems like an unnecessarily roundabout way to calculate this. How about this (pseudocode):

years = current_date.year - start_date.year
if current_date.mmdd < start_date.mmdd:
    years = years - 1

Answer 2

You have counted with 365.4 days in a year which is obviously wrong. If you change that to 365.26 (31558464), leap years will be automatically included in the long run, but not if the period is shorter than 4 years. This is in your own advantage, but not in your employees'.

Also, add a last line to round the number down to completed days:

$servicePeriod = floor($servicePeriod);