Display first/last date of the month from current month during 12 months

date-first-last.php

<?php

// display first/last date of the month from current month during one year
for ($monthToDisplay = 0; $monthToDisplay < 12; $monthToDisplay++)
{
    $f = new \DateTime('first day of this month');
    $l = new \DateTime('last day of this month');
    $df = new \DateInterval('P'.$monthToDisplay.'M');
    $dl = new \DateInterval('P1M');
    $first = $f->add($df)->format('d/m/Y');
    $last = $f->add($dl)->sub(new DateInterval('P1D'))->format('d/m/Y');

    echo $first . " - " . $last . "\n";
}

// will display
    // 01/01/2017 - 31/01/2017
    // 01/02/2017 - 28/02/2017
    // 01/03/2017 - 31/03/2017
    // 01/04/2017 - 30/04/2017
    // ...
    // 01/12/2017 - 31/12/2017