PHP将显示的日期转变为几天、几分钟、几秒前的显示方法

博客的发布时间用到了下面的函数，将博文发布的时间按几天前、几分钟前、几秒前的方式进行转换，以下是函数的示例：

function time_show($time){
        $time_start=$time;
        if ($time==''){
            $time_result='--';
        }else{
            $time=time()-strtotime($time);
            if ($time<=60){ //1分钟以内
                $time_result=$time." 秒前";
                
            }elseif($time<=60*60){ //1小时以内
                $time_result=floor($time/60)." 分钟前";   //ceil向上取整，floor小数部分舍去取整
                
            }elseif($time<=(60*60*24*1)){ //1天以内
                $time_result=floor($time/3600)." 小时前";
                
            }elseif($time<=(60*60*24*4)){ //4天以内
                $time_result=floor($time/3600/24)." 天前";
                
            }else{
                $time_result=date("Y-m-d H:i",strtotime($time_start));
                
            }
        }
        return $time_result;
} 

//调用方法
echo time_show("2015-11-22 12:00:00");