Get letter combinations

combinations.php

<?php

function filterSign($var)
{
	return strlen($var) < 2 ? false : true;
}

function getCombinations($values)
{
	$perms = array(null);
	foreach ($values as $key => $v)
	{
		$temp = $values;
		for ($i=0; $i<=$key; $i++) 
			unset($temp[$i]);

		$newPerms = getCombinations($temp);
		foreach ($newPerms as $perm)
			$perms[] = ($v . $perm);
	}
	return $perms;
}

function getLetterCombinations($word)
{
	$word_array = str_split($word);
	sort($word_array);
	return array_filter(getCombinations($word_array), "filterSign");
}

?>