Php Date difference - Php Datetime object

Example : add and diff method of Datetime object 

Here in below example DateInterval object has the argument like P01Y01M10D
Here the 01Y indicates 1 year
Here the 01M indicates 1 month
Here the 10D indicates 10 days

<?php

    $givendate='2001-01-01';
    //add one year one month and ten days to given date
    $date = new DateTime($givendate);
    $date->add(new DateInterval('P01Y01M10D'));
    echo $date->format('Y-m-d') . "\n";

    //remove one year one month and ten days to given date
    $date = new DateTime($givendate);
    $date->diff(new DateInterval('P01Y01M10D'));
    echo $date->format('Y-m-d') . "\n";

?>

Output:
2002-02-11
2001-01-01

Example : Calculate Age of a Person using Datetime object

<?php

    //Php Date difference - Php Datetime object 
    $birthday="1984-10-18";
    //creating object for birthday
    $birthday = new DateTime($birthday);
    //createing object for current date
    $currentdate = new DateTime();
    //calculate age using php Datetime object method
    $age=$currentdate->diff($birthday);
    print_r($age);

?>

Output:
DateInterval Object (  [y] => 27
 [m] => 10
 [d] => 27
 [h] => 12
 [i] => 38
 [s] => 43
 [invert] => 1
 [days] => 10193
)