« DateTimeImmutable DateTimeImmutable::__construct » PHP Manual DateTimeImmutable Adds an amount of days, months, years, hours, minutes and seconds DateTimeImmutable::add (PHP 5 >= 5.5.0, PHP 7) DateTimeImmutable::add — Adds an amount of days, months, years, hours, minutes and seconds 说明 public DateTimeImmutable::add ( DateInterval $interval ) : DateTimeImmutable Like DateTime::add() but works with DateTimeImmutable.