<?php

function calculateDateDiff($start_date, $end_date)
{
    $diff = date_diff(new DateTime($end_date), new DateTime($start_date));
    echo "month: $diff->m, day: $diff->d ";
}


calculateDateDiff('2016-01-14', '2016-06-12'); echo "\n";
calculateDateDiff('2017-02-14', '2018-01-12'); echo "\n";
calculateDateDiff('2017-02-14', '2017-09-21'); echo "\n";
calculateDateDiff('2017-02-14', '2017-12-02');

?>