文字列表現の日付をタイムスタンプに変換する

$time = '2010/3/31 12:34:56';
$timeStamp = strtotime($time);
$date = date('Y-n-j H:i:s', $timeStamp);
echo sprintf($outputFormat, $time, $timeStamp, $date);

// 2010-1-1（ハイフン区切りの書式）
$timeStamp = strtotime('2010-1-1');
$date = date('Y-n-j H:i:s', $timeStamp);
echo sprintf($outputFormat, '2010-1-1', $timeStamp, $date);

// 現在日付
$timeStamp = strtotime('now');
$date = date('Y-n-j H:i:s', $timeStamp);
echo sprintf($outputFormat, 'now', $timeStamp, $date);

// 1日後（1 day = 86400秒）
$timeStamp = strtotime('+1 day');
$date = date('Y-n-j H:i:s', $timeStamp);
echo sprintf($outputFormat, '+1 day', $timeStamp, $date);

// 1年2ヶ月3週間後
$timeStamp = strtotime('+1 year 2 months 3weeks');
$date = date('Y-n-j H:i:s', $timeStamp);
echo sprintf($outputFormat, '+1 year 2 months 3weeks', $timeStamp, $date);