日付操作　計算

1日後

$date = new DateTime("2009-10-10");

$date->modify("+1 day");

echo $date->format("Y-m-d");

明日

$date = new DateTime("2009-10-10");

$date->modify("tomorrow");

echo $date->format("Y-m-d");

2日後

$date = new DateTime("2009-10-10");

$date->modify("2days ago");

echo $date->format("Y-m-d");

クラスを使わないやり方。

echo "1日前"   . date("Y/m/d", strtotime("-1 day"  ));

echo "1ヶ月前" . date("Y/m/d", strtotime("-1 month"));

echo "1年前"   . date("Y/m/d", strtotime("-1 year" ));

echo "1週間前" . date("Y/m/d", strtotime("-1 week" ));

echo "1日前"   . date("Y/m/d", strtotime("2007/12/20 -1 day"  ));

echo "1ヶ月前" . date("Y/m/d", strtotime("2007/12/20 -1 month"));

echo "1年前"   . date("Y/m/d", strtotime("2007/12/20 -1 year" ));

echo "1週間前" . date("Y/m/d", strtotime("2007/12/20 -1 week" ));