Question

I am trying to get the array elements within a range but failed to do so. Explaining it below.

$date_array = array('2012-08-02','2012-08-09','2012-08-16','2012-08-23');
$start_date = '2012-08-01';
$end_date   = '2012-08-10';

I want to get the array elements from the $date_array within $start_date and $end_date.
i.e, output will be : 2012-08-02 and 2012-08-09.

Edit:

The array can be the following as well.

$date_array = array('2012-08-02','2012-08-10','2012-08-16','2012-08-23');

Answer 1

You can do that using array_filter^Docs and a callback that fulfills your needs:

$filter = function($start, $end) {
    return function($string) use ($start, $end) {
        return $string >= $start && $string <= $end;
    };
};

$result = array_filter($array, $filter('2012-08-01', '2012-08-10'));

Take care of the order of the parameters and as well that you have these exact formats because only those can the done with a simple string comparison.

---

For PHP 5.2 compatibility and also to solve this for iterators and not only arrays, here is a more general approach:

class Range
{
    private $from;
    private $to;
    public function __construct($from, $to) {
        $this->from = $from;
        $this->to = $to;
        if ($from > $to) {
            $this->reverse();
        }
    }
    private function reverse() {
        list($this->from, $this->to) = array($this->to, $this->from);
    }
    public function in($value) {
        return $this->from <= $value && $value <= $this->to;
    }
}

class RangeFilter extends FilterIterator
{
    private $range;
    public function __construct(Iterator $iterator, Range $range) {
        $this->range = $range;
        parent::__construct($iterator);
    }

    public function accept()
    {
        $value = $this->getInnerIterator()->current();
        return $this->range->in($value);
    }
}

$range = new Range($start, $end);
$it = new ArrayIterator($array);
$filtered = new RangeFilter($it, $range);
$result = iterator_to_array($filtered);