PHP를 사용하여 아라비아 숫자를 대문자로 변환하는 방법

function arabicToUpperCase($arabic) {
    $units = array('','one','two','three','four','five','six','seven','eight','nine');
    $teens = array('ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen','seventeen','eighteen','nineteen');
    $tens = array('','ten','twenty','thirty','forty','fifty','sixty','seventy','eighty','ninety');
    $hundreds = array('','one hundred','two hundred','three hundred','four hundred','five hundred','six hundred','seven hundred','eight hundred','nine hundred');
    $thousands = array('','one thousand','two thousand','three thousand','four thousand','five thousand','six thousand','seven thousand','eight thousand','nine thousand');

    $parts = explode('.', $arabic);
    $integer = $parts[0];

    if($integer == 0) {
        return 'zero';
    }

    $digits = str_split($integer);
    $digits = array_reverse($digits);

    $result = array();
    for($i = 0; $i < count($digits); $i++) {
        switch($i) {
            case 0:
                $result[] = $units[$digits[$i]];
                break;
            case 1:
                if($digits[$i] == 1) {
                    $result[] = $teens[$digits[$i-1]];
                    $result[] = $tens[$digits[$i]];
                } else {
                    $result[] = $tens[$digits[$i]];
                }
                break;
            case 2:
                $result[] = $hundreds[$digits[$i]];
                break;
            case 3:
                $result[] = $thousands[$digits[$i]];
                break;
        }
    }

    $result = array_reverse($result);
    return join(' ', $result);
}

echo arabicToUpperCase('1234567');