php计算到指定的日期还有多少天

php计算到指定的日期还有多少天

function countdays($d)
{
 $olddate =  substr($d, 4);
 $newdate = date(Y) ."".$olddate;
 $nextyear = date(Y)+1 ."".$olddate;
 
    if($newdate > date("Y-m-d"))
    {
    $start_ts = strtotime($newdate);
    $end_ts = strtotime(date("Y-m-d"));
    $diff = $end_ts - $start_ts;
    $n = round($diff / 86400);
    $return = substr($n, 1);
    return $return;
    }
    else
    {
    $start_ts = strtotime($nextyear);
    $end_ts = strtotime(date("Y-m-d"));
    $diff = $end_ts - $start_ts;
    $n = round($diff / 86400);
    $return = substr($n, 1);
    return $return;
 
    }
 
}