Display the total number of days between two dates in PHP

$date1 = new DateTime('2020-01-01'); 
$date2 = new DateTime('2020-02-15'); 
print_r($date1->diff($date2));

DateInterval Object ( 
  [y] => 0 
  [m] => 1 
  [d] => 14 
  [h] => 0 
  [i] => 0 
  [s] => 0 
  [f] => 0 
  [weekday] => 0 
  [weekday_behavior] => 0 
  [first_last_day_of] => 0 
  [invert] => 0 
  [days] => 45 
  [special_type] => 0 
  [special_amount] => 0 
  [have_weekday_relative] => 0 
  [have_special_relative] => 0 
)