Use of PHP time class

<?php
header("Content-type:text/html;Charset=utf-8");
class time{
 private $year;//年
 private $month;//月
 private $day;//天
 private $hour;//小时
 private $minute;//分钟
 private $second;//秒
 private $microtime;//毫秒
 private $weekday;//星期
 private $longDate;//完整的时间格式
 private $diffTime;//两个时间的差值
 //返回年份 time：时间格式为时间戳  2013-3-27
 function getyear($time="",$type=""){
 if($time==""){
  $time=time();
 }
 if($type==1){
  return $this->year=date("y",$time); //返回两位的年份 13
 }else{
  return $this->year=date("Y",$time); //返回四位的年份 2013
 }
 }
 //返回当前时间的月份 time：时间格式为时间戳 2013-3-27
 function getmonth($time="",$type=""){
 if($time==""){
  $time=time();
 }
 switch($type){
  case 1:$this->month=date("n",$time);//返回格式 3
   break;
  case 2:$this->month=date("m",$time);//返回格式 03
   break;
  case 3:$this->month=date("M",$time);//返回格式 Mar
   break;
  case 4:$this->month=date("F",$time);//返回格式 March
   break;
  default:$this->month=date("n",$time);
 }
 return $this->month; 
 }
 //返回当前时间的天数 time：时间格式为时间戳 2013-3-4 
 function getday($time="",$type=""){
 if($time==""){
  $time=time();
 }
 if($type==1){
  $this->day=date("d",$time);//返回格式 04
 }else{
  $this->day=date("j",$time);//返回格式 4
 }
 return $this->day;
 }
 //返回当前时间的小时  2010-11-10 1:19:21 20:19:21 
 function gethour($time="",$type=""){
 if($time==""){
  $time=time();
 } 
 switch($type){
  case 1:$this->hour=date("H",$time);//格式： 1 20
   break;
  case 2:$this->hour=date("h",$time);//格式  01 08
   break;
  case 3:$this->hour=date("G",$time);//格式  1 20
   break;
  case 4:$this->hour=date("g",$time);//格式  1 8
   break; 
  default :$this->hour=date("H",$time);
 }
 return $this->hour;
 }
 //返回当前时间的分钟数 1:9:18  
 function getminute($time="",$type=""){
 if($time==""){
  $time=time();
 }
 $this->minute=date("i",$time); //格式  09
 return $this->minute;
 }
 //返回当前时间的秒数  20:19:01
 function getsecond($time="",$type=""){
 if($time==""){
  $time=time();
 }
 $this->second=date("s",$time); //格式  01
 return $this->second;
 }
 //返回当前时间的星期数 
 function getweekday($time="",$type=""){
 if($time==""){
  $time=time(); 
 }
 if($type==1){
  $this->weekday=date("D",$time);//格式  Sun
 }else if($type==2){
  $this->weekday=date("l",$time); //格式 Sunday
 }else{
  $this->weekday=date("w",$time);//格式 数字表示 0--6
 }
 return $this->weekday;
 }
 //比较两个时间的大小 格式 2013-3-4 8:4:3  
 function compare($time1,$time2){
 $time1=strtotime($time1);
 $time2=strtotime($time2);
 if($time1>=$time2){  //第一个时间大于等于第二个时间 返回1 否则返回0
  return 1;
 }else{
  return -1;
 }
 }
 //比较两个时间的差值
 function diffdate($time1="",$time2=""){
 //echo $time1.&#39;------&#39;.$time2.&#39;<br>&#39;;
 if($time1==""){
  $time1=date("Y-m-d H:i:s"); 
 }
 if($time2==""){ 
  $time2=date("Y-m-d H:i:s"); 
 }
 $date1=strtotime($time1);
 $date2=strtotime($time2);
 if($date1>$date2){
  $diff=$date1-$date2; 
 }else{
  $diff=$date2-$date1;
 }
 if($diff>=0){
  $day=floor($diff/86400);
  $hour=floor(($diff%86400)/3600);
  $minute=floor(($diff%3600)/60);
  $second=floor(($diff%60));
  $this->diffTime=&#39;相差&#39;.$day.&#39;天&#39;.$hour.&#39;小时&#39;.$minute.&#39;分钟&#39;.$second.&#39;秒&#39;; 
 }
 return $this->diffTime;
 }
 //返回 X年X月X日
 function buildDate($time="",$type=""){
 if($type==1){   
  $this->longDate = $this->getyear($time) . &#39;年&#39; . $this->getmonth($time) . &#39;月&#39; . $this->getday($time) . &#39;日&#39;;  
 }else{
  $this->longDate = $this->getyear($time) . &#39;年&#39; . $this->getmonth($time) . &#39;月&#39; . $this->getday($time) . &#39;日&#39;.$this->gethour($time).&#39;:&#39;.$this->getminute($time).&#39;:&#39;.$this->getsecond($time);  
 }
 return $this->longDate;  
 }
}
?>