note 88679 deleted from function.strtotime by derick

Note Submitter: akniep at rayo dot info ---- The "+1 month" issue solved as in MySQL. ======================================== As noted in several comments, PHP's strtotime() solves the "+1 month" ("next month") issue on days that do not exist in the subsequent month differently than other implementations like for example MySQL. // PHP: 2009-03-03 <?php echo date( "Y-m-d", strtotime( "2009-01-31 +1 month" ) ); ?> // MySQL: 2009-02-28 <?php SELECT DATE_ADD( '2009-01-31', INTERVAL 1 MONTH ); ?> ======================================== If not for consistency with MySQL there are several reasons why one may need a PHP-function that calculates "+1 month" as MySQL does. Certainly, for various kinds of business logic it seems much more intuitiv to land on a date within the subsequent month rather than on a date within the next but one if you calculate "next month" ("+1 month"). The following function calculates a date X months in the future of a given date ($base_time). <?php /** * Calculates a date lying a given number of months in the future of a given date. * The results resemble the logic used in MySQL where '2009-01-31 +1 month' is '2009-02-28' rather than '2009-03-03' (like in PHP's strtotime). * * @author akniep * @since 2009-02-03 * @param $base_time long, The timestamp used to calculate the returned value . * @param $months int, The number of months to jump to the future of the given $base_time. * @return long, The timestamp of the day $months months in the future of $base_time */ function get_x_months_to_the_future( $base_time = null, $months = 1 ) { if (is_null($base_time)) $base_time = time(); $x_months_to_the_future = strtotime( "+" . $months . " months", $base_time ); $month_before = (int) date( "m", $base_time ) + 12 * (int) date( "Y", $base_time ); $month_after = (int) date( "m", $x_months_to_the_future ) + 12 * (int) date( "Y", $x_months_to_the_future ); if ($month_after > $months + $month_before) $x_months_to_the_future = strtotime( date("Ym01His", $x_months_to_the_future) . " -1 day" ); return $x_months_to_the_future; } //get_x_months_to_the_future() // Tests // ======= // returns 2009-02-28 echo date( "Y-m-d H:i:s", get_x_months_to_the_future( strtotime( '2009-01-31' ) ) ), "\n"; // returns 2008-02-29 echo date( "Y-m-d H:i:s", get_x_months_to_the_future( strtotime( '2008-01-31' ) ) ), "\n"; // returns 2009-09-30 12:00:00 echo date( "Y-m-d H:i:s", get_x_months_to_the_future( strtotime( '2009-05-31 12:00:00' ), 4 ) ), "\n"; ?>