Online PHP editor | refs for SjYiE

<?php function add_one_month($date) { // find the next month $nextmonth = mktime(0, 0, 0, date("n", $date) + 1, 1, date("Y", $date)); // limit the day number according to the month $day = min(date("t", $nextmonth), date("j", $date)); // combine into desired date return mktime(0, 0, 0, date("n", $nextmonth), $day, date("Y", $nextmonth)); } for ($d = 20; $d <= 31; $d++) { $date = mktime(0, 0, 0, 1, $d, 2017); $normal = date("Y-m-d", strtotime("+1 month", $date)); $addonemonth = date("Y-m-d", add_one_month($date)); printf("2017-01-%02d: +1 month = %s add_one_month = %s\n", $d, $normal, $addonemonth); }