Problem with the returning value from stripos

Assuming that $arr1 is an array, and $haystack is a string, when I call this method into my class, it doesn’t respond properly.

$arr1 = [];

// This is a function that generate every string combinations from needle ('dio', 'iod', 'odi', etc)
function permute();

class checkAnagram {
    public function anagram(string $needle, string $haystack, &$arr1): bool {
        if ((strlen($needle) > 1024 || strlen($haystack) > 1024) || strlen($needle) > strlen($haystack)) {
            return 0;
        }

        $needle = strtolower($needle);
        $haystack = strtolower($haystack);

        $str = strtolower($needle);
        permute($str, 0, strlen($str), $arr1);

        for ($i = 0; $i < count($arr1); $i++) {
            if (stripos($haystack, $arr1[$i]) !== false) {
                return true;
            }
        }
        return false;
    }
}

$amara = new checkAnagram();
echo $amara->anagram('Dio', 'Aasadio', $arr1);

It ends to echo nothing, false neither.

>Solution :

Your arguments are reversed in stripos. $haystack should come first. Echoing true will return 1, false will return nothing, which is why you aren’t seeing anything.