PHP 处理日期、时间、时间戳相关操作

//时间相关
    public function timeinfo(){

        //获取今天0点-24点时间戳
        $today = strtotime(date('Y-m-d', time()));
        $todayend = $today + 24 * 60 * 60;

        //获取本周第一天及最后一天
        $weekfirst=strtotime(date('Y-m-d', strtotime('this week')));
        $weeklast=strtotime(date('Y-m-d', strtotime('last day next week')));

        //3.获取当天年份、月份、日及天数.
        echo " 本月共有:".date("t")."天";
        echo " 当前年份".date('Y');
        echo " 当前月份".date('m');
        echo " 当前几号".date('d');

        //1.获取上个月第一天及最后一天.
        echo date('Y-m-01', strtotime('-1 month'));
        echo "<br/>";
        echo date('Y-m-t', strtotime('-1 month'));

        //2016-08-10这天 2个月后的日期
        echo date("Y-m-d",strtotime("+2 month",strtotime("2016-08-10")));

        //获取3 年、月、日 后的日期
        echo date("Y-m-d",strtotime("+3 year",time()));
        echo date("Y-m-d",strtotime("+3 month",time()));
        echo date("Y-m-d",strtotime("+3 day",time()));

        //获取今天、昨天、明天的日期
        echo "今天:".date("Y-m-d")."<br>";       
        echo "昨天:".date("Y-m-d",strtotime("-1 day")), "<br>";       
        echo "明天:".date("Y-m-d",strtotime("+1 day")). "<br>";    
        echo "一周后:".date("Y-m-d",strtotime("+1 week")). "<br>";       
        echo "一周零两天四小时两秒后:".date("Y-m-d G:H:s",strtotime("+1 week 2 days 4 hours 2 seconds")). "<br>";       
        echo "下个星期四:".date("Y-m-d",strtotime("next Thursday")). "<br>";       
        echo "上个周一:".date("Y-m-d",strtotime("last Monday"))."<br>";       
        echo "一个月前:".date("Y-m-d",strtotime("last month"))."<br>";       
        echo "一个月后:".date("Y-m-d",strtotime("+1 month"))."<br>";       
        echo "十年后:".date("Y-m-d",strtotime("+10 year"))."<br>";        

    }

    //获取当月第一天和最后一天
    function getthemonth($date)
    {
        $firstday = date('Y-m-01', strtotime(date('Y-m-d')));
        $lastday = date('Y-m-d', strtotime("$firstday +1 month -1 day"));
        return array($firstday,$lastday);
    }

    //计算两个时间戳相差天数
    function timediff($begin_time,$end_time)
    {
        if($begin_time < $end_time){
            $starttime = $begin_time;
            $endtime = $end_time;
        }else{
            $starttime = $end_time;
            $endtime = $begin_time;
        }
        //计算天数
        $timediff = $endtime-$starttime;
        $days = intval($timediff/86400);
        //计算小时数
        $remain = $timediff%86400;
        $hours = intval($remain/3600);
        //计算分钟数
        $remain = $remain%3600;
        $mins = intval($remain/60);
        //计算秒数
        $secs = $remain%60;
        $res = array("day" => $days,"hour" => $hours,"min" => $mins,"sec" => $secs);
        return $res;
    }