在一串日期中合并连续的日期

输入：'2016-02-01','2016-02-02','2016-02-03','2016-02-04','2016-02-05','2016-02-06','2016-02-07','2016-02-08','2016-02-09','2016-02-10','2016-02-11','2016-02-13','2016-02-14','2016-02-16'

输出：2016-02-01到2016-02-11,2016-02-13到2016-02-14,2016-02-16

代码：

<?php
$a = ['2016-02-01','2016-02-02','2016-02-03','2016-02-04','2016-02-05','2016-02-06','2016-02-07','2016-02-08','2016-02-09','2016-02-10','2016-02-11','2016-02-13','2016-02-14','2016-02-16'];
$c = array();
$length = count($a);
$today = new DateTime();
$oneDayInterval = new DateInterval('P1D');
$temp[] = $a[0];
for($i=0;$i<$length;$i++){
    if(DateTime::createFromFormat('Y-m-d',$a[$i])->add($oneDayInterval) == DateTime::createFromFormat('Y-m-d',$a[$i+1])){
        $temp[] = $a[$i+1];
    }else{
        $c[] = $temp;
        $temp = [];
        $temp[] = $a[$i+1];
    }
}
foreach($c as &$value){
    if(count($value) > 1){
        $value = current($value).'到'.end($value);
    }else{
        $value = implode(',',$value);
    }
}
unset($value);
$d = implode(',',$c);
var_dump($d);