$dt = Carbon::create(2012, 1, 31, 0);
echo $dt->toDateTimeString(); // 2012-01-31 00:00:00
echo $dt->addCenturies(5); // 2512-01-31 00:00:00
echo $dt->addCentury(); // 2612-01-31 00:00:00
echo $dt->subCentury(); // 2512-01-31 00:00:00
echo $dt->subCenturies(5); // 2012-01-31 00:00:00
echo $dt->addYears(5); // 2017-01-31 00:00:00
echo $dt->addYear(); // 2018-01-31 00:00:00
echo $dt->subYear(); // 2017-01-31 00:00:00
echo $dt->subYears(5); // 2012-01-31 00:00:00
echo $dt->addQuarters(2); // 2012-07-31 00:00:00
echo $dt->addQuarter(); // 2012-10-31 00:00:00
echo $dt->subQuarter(); // 2012-07-31 00:00:00
echo $dt->subQuarters(2); // 2012-01-31 00:00:00
echo $dt->addMonths(60); // 2017-01-31 00:00:00
echo $dt->addMonth(); // 2017-03-03 00:00:00 equivalent of $dt->month($dt->month + 1); so it wraps
echo $dt->subMonth(); // 2017-02-03 00:00:00
echo $dt->subMonths(60); // 2012-02-03 00:00:00
echo $dt->addDays(29); // 2012-03-03 00:00:00
echo $dt->addDay(); // 2012-03-04 00:00:00
echo $dt->subDay(); // 2012-03-03 00:00:00
echo $dt->subDays(29); // 2012-02-03 00:00:00
echo $dt->addWeekdays(4); // 2012-02-09 00:00:00
echo $dt->addWeekday(); // 2012-02-10 00:00:00
echo $dt->subWeekday(); // 2012-02-09 00:00:00
echo $dt->subWeekdays(4); // 2012-02-03 00:00:00
echo $dt->addWeeks(3); // 2012-02-24 00:00:00
echo $dt->addWeek(); // 2012-03-02 00:00:00
echo $dt->subWeek(); // 2012-02-24 00:00:00
echo $dt->subWeeks(3); // 2012-02-03 00:00:00
echo $dt->addHours(24); // 2012-02-04 00:00:00
echo $dt->addHour(); // 2012-02-04 01:00:00
echo $dt->subHour(); // 2012-02-04 00:00:00
echo $dt->subHours(24); // 2012-02-03 00:00:00
echo $dt->addMinutes(61); // 2012-02-03 01:01:00
echo $dt->addMinute(); // 2012-02-03 01:02:00
echo $dt->subMinute(); // 2012-02-03 01:01:00
echo $dt->subMinutes(61); // 2012-02-03 00:00:00
echo $dt->addSeconds(61); // 2012-02-03 00:01:01
echo $dt->addSecond(); // 2012-02-03 00:01:02
echo $dt->subSecond(); // 2012-02-03 00:01:01
echo $dt->subSeconds(61); // 2012-02-03 00:00:00
echo $dt->addMilliseconds(61); // 2012-02-03 00:00:00
echo $dt->addMillisecond(); // 2012-02-03 00:00:00
echo $dt->subMillisecond(); // 2012-02-03 00:00:00
echo $dt->subMillisecond(61); // 2012-02-03 00:00:00
echo $dt->addMicroseconds(61); // 2012-02-03 00:00:00
echo $dt->addMicrosecond(); // 2012-02-03 00:00:00
echo $dt->subMicrosecond(); // 2012-02-03 00:00:00
echo $dt->subMicroseconds(61); // 2012-02-03 00:00:00
// and so on for any unit: millenium, century, decade, year, quarter, month, week, day, weekday,
// hour, minute, second, microsecond.
// Generic methods add/sub (or subtract alias) can take many different arguments:
echo $dt->add(61, 'seconds'); // 2012-02-03 00:01:01
echo $dt->sub('1 day'); // 2012-02-02 00:01:01
echo $dt->add(CarbonInterval::months(2)); // 2012-04-02 00:01:01
echo $dt->subtract(new DateInterval('PT1H')); // 2012-04-01 23:01:01