まとめ 基本的にはDateTimeImmutableを使え DatePeriodで事足りる場合は多い。 DateTimeを使わない例 $todayとか$tomorrowとかには使わない(DateTimeImmutableを使え) 例えば、知らずに以下のようなコードを書くと、ハマります。 <?php // 例えば、2016-06-15 15:48 $tomorrow = new DateTime(); // ここで、2016-06-16 15:48になる。 $tomorrow->add(new DatetimeInterval('P1D')); // どこか知らな場所でこういうことをやると… $dayAfterTomorrow = $tomorrow->add(new DatetimeInterval('P1D')); // $tomorrow 変数が、tomorrowじゃなくなった!!!!
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