Calendar

0 && $_month<=12) {$month = $_month;} } // years divisible by 4 are leap, unless // divisible by 100, then only years divisible // by 400 are leapers. function isLeap($yr) { $ret = false; if($yr % 4 == 0) { // possible if($yr % 400 == 0) { $ret = true; } else if($yr % 100 != 0) { $ret = true; } } return $ret; } $mo_keys=array( 1=>1, 2=>4, 3=>4, 4=>0, 5=>2, 6=>5, 7=>0, 8=>3, 9=>6, 10=>1, 11=>4, 12=>6 ); // 1700-2000 original. My update: century/100 %4. $cent_keys=array( 1 => 4, 2 => 2, 3 => 0, 0 => 6 ); // Formula from Ask Dr. Math: mathforum.org // Key Value method (repeats every 400 years) // year Last-2 div 4 (discard remainder) // Add day of month // Add month key value from table // -1 if Jan/Feb // + century code from table // + year last-2 // %7 : 1 is Sunday, 0 Saturday // function adjusts 0=Sunday, 6=Saturday function getDayofWeek($yr, $mo, $day) { global $mo_keys, $cent_keys; $last2 = $yr % 100; $wrk = intdiv($last2, 4); $wrk += $day + $mo_keys[$mo]; if(($mo < 3) && isLeap($yr)) { $wrk -= 1;} $cent_idx = (($yr-$last2)/100) % 4; $wrk += $cent_keys[$cent_idx]; $wrk += $last2; $dow = ($wrk % 7)-1; if($dow==-1){$dow=6;} // 0-6, Sunday 1st return $dow; } // There are 14 calendars on a 28-year cycle, // but all I need is day 1 of requested month. $monthStartsOn = getDayofWeek($year, $month, 1); $daysInMonth=array( 31,28,31,30,31,30,31, 31,30,31,30,31); $dim = $daysInMonth[$month-1]; if($dim==2 && isLeap($year)) {$dim += 1;} $json = json_encode( array( 'startDOW' => $monthStartsOn, 'daysInMonth' => $dim, 'month' => $month, 'year' => $year ) ); // =========================================== // send response to client, "close" connection // =========================================== ?>Calendar English, Spanish, German, French, Lithuanian text (by browser language). All calendars BUT English start on Monday

Current month's "start day" of the week (1-7) is calculated by server "manually" (perpetual calendar algorithm) - JSON is returned so calendar can be drawn by client.

PHP accepts POST and GET (year and month), returns JSON. Simulates client/server model.

Calendar; first day calc + localization