php 多长时间之前 的函数

```php<?php  /*  * author: china_skag  * time: 2014-07-08  * 发博时间计算(年，月，日，时，分，秒)  * $createtime 可以是当前时间  * $gettime 你要传进来的时间  */  class Mygettime{          function  __construct($createtime,$gettime) {              $this->createtime = $createtime;              $this->gettime = $gettime;      }      function getSeconds()      {              return $this->createtime-$this->gettime;          }      function getMinutes()         {         return ($this->createtime-$this->gettime)/(60);         }        function getHours()         {         return ($this->createtime-$this->gettime)/(60*60);         }        function getDay()         {          return ($this->createtime-$this->gettime)/(60*60*24);         }        function getMonth()         {          return ($this->createtime-$this->gettime)/(60*60*24*30);         }         function getYear()         {          return ($this->createtime-$this->gettime)/(60*60*24*30*12);         }         function index()         {              if($this->getYear() > 1)              {                   if($this->getYear() > 2)                      {                          return date("Y-m-d",$this->gettime);                          exit();                      }                  return intval($this->getYear())." 年前";                  exit();              }               if($this->getMonth() > 1)              {                  return intval($this->getMonth())." 月前";                  exit();              }               if($this->getDay() > 1)              {                  return intval($this->getDay())." 天前";                  exit();              }               if($this->getHours() > 1)              {                  return intval($this->getHours())." 小时前";                  exit();              }               if($this->getMinutes() > 1)              {                  return intval($this->getMinutes())." 分钟前";                  exit();              }             if($this->getSeconds() > 1)              {                  return intval($this->getSeconds()-1)." 秒前";                  exit();              }         }    }  //类的使用实例  /*  *  * 调用类输出方式  *  * $a = new Mygettime(time(),strtotime('-25 month'));  * echo iconv('utf-8', 'gb2312', $a->index())?iconv('utf-8', 'gb2312', $a->index()):iconv('utf-8', 'gb2312', '当前');  *  */  ```