php计算两个时间相差的天数、小时数、分钟数、秒数

//$startdate是开始时间，$enddate是结束时间

$startdate="2011-3-15 11:50:00";

$enddate="2012-12-12 12:12:12";

$date=floor((strtotime($enddate)-strtotime($startdate))/86400);

echo "相差天数：".$date."天";

$hour=floor((strtotime($enddate)-strtotime($startdate))%86400/3600);

echo "相差小时数：".$hour."小时";

$minute=floor((strtotime($enddate)-strtotime($startdate))%86400/60);

echo "相差分钟数：".$minute."分钟";

$second=floor((strtotime($enddate)-strtotime($startdate))%86400%60);

echo "相差秒数：".$second."秒";

?>