php計算兩個日期相差月數精確到天

/*
 * $date1 = Y-m-d H:i:s
 * $date2 = Y-m-d H:i:s
 * */
function getMonthNums($date1,$date2){
    $date1 = date("Y-m-d",strtotime($date1));
    $date2 = date("Y-m-d",strtotime($date2));
    if(strtotime($date1)>strtotime($date2)){
        $tmp=$date2;
        $date2=$date1;
        $date1=$tmp;
    }
    list($Y1,$m1,$d1)=explode('-',$date1);
    list($Y2,$m2,$d2)=explode('-',$date2);
    $y=$Y2-$Y1;
    $m=$m2-$m1;
    $d=$d2-$d1;
    if($d<0){
        $d+=(int)date('t',strtotime("-1 month $date2"));
        $m--;
    }
    if($m<0){
        $m+=12;
        $y--;
    }
    $mounth = $y*12+$m;
    return $mounth;
}