php 取开始时间和结束时间所跨越的所有季度时间

/*
 *   由起止日期算出其中所跨的季度 和各季度开始结束时间
 *   params
 *       $st:开始日期 Y-m-d格式
 *       $et:结束日期 Y-m-d格式
 */
function getQuarter($st,$et){
    $stime = strtotime($st);
    $etime = strtotime($et);
    if($stime > $etime){
        $tpTime = $stime;
        $stime = $etime;
        $etime = $tpTime;
    }
    //取开始时间是属于第几季度
    $season_st = ceil((date('n',$stime))/3);
    $year_st = date('Y',$stime);
    //取结束时间是属于第几季度
    $season_et = ceil((date('n',$etime))/3);
    $year_et = date('Y',$etime);
    //echo $year_st.$season_st,$year_et.$season_et;
    $return = array();
    $times = array();
    if($year_st == $year_et){ //同一年内
        $return[$year_st.'Q'.$season_st] = 0;
        $times[$year_st.'Q'.$season_st][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$season_st*3-3+1,1,$year_st));
        $times[$year_st.'Q'.$season_st][1] = date('Y-m-d H:i:s', mktime(23,59,59,$season_st*3,date('t',mktime(0, 0 , 0,$season_st*3,1,$year_st)),$year_st));
        while($season_st != $season_et){
            $season_st++;
            $return[$year_st.'Q'.$season_st] = 0;
            $times[$year_st.'Q'.$season_st][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$season_st*3-3+1,1,$year_st));
            $times[$year_st.'Q'.$season_st][1] = date('Y-m-d H:i:s', mktime(23,59,59,$season_st*3,date('t',mktime(0, 0 , 0,$season_st*3,1,$year_st)),$year_st));
        }
        
    }else{
        for($i=$year_st,$j=$year_et,$i_st=$season_st,$i_et=$season_et;$i<=$j;$i++){
            $return[$year_st.'Q'.$i_st] = 0;
            $times[$year_st.'Q'.$season_st][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$season_st*3-3+1,1,$year_st));
            $times[$year_st.'Q'.$season_st][1] = date('Y-m-d H:i:s', mktime(23,59,59,$season_st*3,date('t',mktime(0, 0 , 0,$season_st*3,1,$year_st)),$year_st));
            if($i == $year_st){
                while($i_st <4){
                    $i_st++;
                    $return[$i.'Q'.$i_st] = 0;
                    $times[$i.'Q'.$i_st][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$i_st*3-3+1,1,$i));
                    $times[$i.'Q'.$i_st][1] = date('Y-m-d H:i:s', mktime(23,59,59,$i_st*3,date('t',mktime(0, 0 , 0,$i_st*3,1,$i)),$i));
                }
            }
            elseif($i != $j){
                for($k=1;$k<=4;$k++){
                    $return[$i.'Q'.$k] = 0;
                    $times[$i.'Q'.$k][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$k*3-3+1,1,$i));
                    $times[$i.'Q'.$k][1] = date('Y-m-d H:i:s', mktime(23,59,59,$k*3,date('t',mktime(0, 0 , 0,$k*3,1,$i)),$i));
                }
            }
            else{//同一年了
                for($k=1;$k<=$i_et;$k++){
                    $return[$i.'Q'.$k] = 0;
                    $times[$i.'Q'.$k][0] = date('Y-m-d H:i:s', mktime(0, 0, 0,$k*3-3+1,1,$i));
                    $times[$i.'Q'.$k][1] = date('Y-m-d H:i:s', mktime(23,59,59,$k*3,date('t',mktime(0, 0 , 0,$k*3,1,$i)),$i));
                }
            }
        }
    }
    return $times;
} 
/*
 * 取某个季度的开始和结束时间
 *   $year 年份，如2014
 *   $season 季度，1、2、3、4
 */
function getQuarterDate($year,$season){
    $times = array();
    $times['st'] = date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,$year));
    $times['et'] = date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0 , 0,$season*3,1,$year)),$year));
    return $times;
}

例：

getQuarter（'2011-09-08','2014-07-11'）;
结果：

Array
(
    [2011Q3] => Array
        (
            [0] => 2011-07-01 00:00:00
            [1] => 2011-09-30 23:59:59
        )

    [2011Q4] => Array
        (
            [0] => 2011-10-01 00:00:00
            [1] => 2011-12-31 23:59:59
        )

    [2012Q1] => Array
        (
            [0] => 2012-01-01 00:00:00
            [1] => 2012-03-31 23:59:59
        )

    [2012Q2] => Array
        (
            [0] => 2012-04-01 00:00:00
            [1] => 2012-06-30 23:59:59
        )

    [2012Q3] => Array
        (
            [0] => 2012-07-01 00:00:00
            [1] => 2012-09-30 23:59:59
        )

    [2012Q4] => Array
        (
            [0] => 2012-10-01 00:00:00
            [1] => 2012-12-31 23:59:59
        )

    [2013Q1] => Array
        (
            [0] => 2013-01-01 00:00:00
            [1] => 2013-03-31 23:59:59
        )

    [2013Q2] => Array
        (
            [0] => 2013-04-01 00:00:00
            [1] => 2013-06-30 23:59:59
        )

    [2013Q3] => Array
        (
            [0] => 2013-07-01 00:00:00
            [1] => 2013-09-30 23:59:59
        )

    [2013Q4] => Array
        (
            [0] => 2013-10-01 00:00:00
            [1] => 2013-12-31 23:59:59
        )

    [2014Q1] => Array
        (
            [0] => 2014-01-01 00:00:00
            [1] => 2014-03-31 23:59:59
        )

    [2014Q2] => Array
        (
            [0] => 2014-04-01 00:00:00
            [1] => 2014-06-30 23:59:59
        )

    [2014Q3] => Array
        (
            [0] => 2014-07-01 00:00:00
            [1] => 2014-09-30 23:59:59
        )

)

getQuarter（'2014-06-28','2014-07-11'）;

结果：
Array
(
    [2014Q2] => Array
        (
            [0] => 2014-04-01 00:00:00
            [1] => 2014-06-30 23:59:59
        )

    [2014Q3] => Array
        (
            [0] => 2014-07-01 00:00:00
            [1] => 2014-09-30 23:59:59
        )

)