Czech date interval format

date_interval.php

<?php

function date_interval(DateTime $begin, DateTime $end = NULL)
{
	if (!$end) {
		return $begin->format('j. n. Y');
	}

	$begin = array_reverse(str_split($begin->format('j. n. Y')));
	$end = array_reverse(str_split($end->format('j. n. Y')));

	$pos = count($begin);
	foreach ($begin as $key => $val) {
		if ($val !== $end[$key]) {
			$pos = $key;
			break;
		}
	}

	$begin = array_slice($begin, $pos > 0 ? $pos - 1 : 0);

	$str = implode('', array_reverse($end));
	if (count($begin) > 1) {
		$str = implode('', array_reverse($begin)) . ' – ' . $str;
	}

	return $str;
}

echo date_interval(new DateTime('2015-02-25'), new DateTime('2015-02-25')) . "<br>\n";
echo date_interval(new DateTime('2015-02-25'), new DateTime('2015-02-26')) . "<br>\n";
echo date_interval(new DateTime('2015-02-25'), new DateTime('2015-03-26')) . "<br>\n";
echo date_interval(new DateTime('2015-02-25'), new DateTime('2016-03-26')) . "<br>\n";