function getAlphabetList($list = null)
{
    $alphabet = split(' ', 'A B C D E F G H I J K L M N O P Q R S T U V W X Y Z');

    foreach($alphabet as $letter)
    {
        $has_letter = false;
        if(is_array($list))
        {
            foreach ($list as $value)
            {
                    if(substr(strtoupper($value),0,1) == strpos($letter,$value,1))
                    {
                        $has_letter = true;
                    }
            }
        }

        if($has_letter)
        {
            $output .= '<a href="?letter='.$letter.'">'.$letter.'</a> ';
        } else {
            $output .= $letter.' ';
        }
    }
    return $output;
}