php - Difference between the current date and the birthday date inserted in a form -

on form, user must enter date of birth. php should control if has accomplished 18 years.

$birth = $_post['data_nascita'];  $str_birth = strtotime ($birth );          $today = date("m/d/y"); $str_today = strtotime ($today);                  if($today - $str_today < 567648000) {     echo'you can't drive car in italy because underage';exit();  } // 18 years * 31536000 second in 1 year = 567648000 

if put on birth field date of 14 september 1998 (today 13 september 2016, 18 years don't entirely spend yet), control doesn't work; works starting 15 september 1998.

why lost 2 days?

i recommend using datetime class has date , time functionality , maths built it.

an example:

$birth = new datetime($_post['date_of_birth']); $today = new datetime('now');  $diff = $birth->diff($today);  if($diff->format('%y') > 18) {     echo "can drive"; } else {     echo "can't drive"; }