Php calculate time difference php date conversion example

I implemented a code to calculate the time difference and counted the number of days. I remembered that I had seen the conversion into months and days in other programs, so I started writing it. It was actually very simple, just a few conversions, but it was not in monthly statistics. It's very accurate, because I don't know how many days it is calculated when I convert it into a month, so I converted it into a month with 30 days. The error shouldn't be big, but this cannot be solved.

Example, code to calculate website building time: $jztime website creation time format: 2013-01-01

$days = abs(strtotime($jztime) - strtotime(date("Y-m-d")))/86400;
if ($days>365){
$site_Y=intval( $days/365)."Year-";
}
if ($days>31){
$str=explode(".",$days/365);//Get the remaining data of the year
$site_m = ( "0.".$str[(count($str)-1)])*365/30;
$site_m = intval($site_m)."月-";
} bbs.it-home.org
if ($days>1){
$str=explode(".",$days/365);//Continue to obtain the remaining data
$site_d = ("0.".$str[(count($str)- 1)])*365-(intval($site_m)*30);
$site_d = intval($site_d)."Day";
}
$dayst= $site_Y.$site_m.$site_d;
echo $dayst ;
?>