PHPで数字を大文字に変換する方法

/**
 * 金额的小写转大写
 * @param $ns int 输入的数字
 */
 function cny($ns) {
    static $cnums = array("零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"),    
    $cnyunits = array("圆", "角", "分"),    
    $grees = array("拾", "佰", "仟", "万", "拾", "佰", "仟", "亿");    
    list($ns1, $ns2) = explode(".", $ns, 2);    
    $ns2 = array_filter(array($ns2[1], $ns2[0]));    
    $ret = array_merge($ns2, array(implode("", _cny_map_unit(str_split($ns1), $grees)), ""));    
    $ret = implode("", array_reverse(_cny_map_unit($ret, $cnyunitss)));    
    return str_replace(array_keys($cnums), $cnums, $ret);
}
function _cny_map_unit($list, $units) {
    $ul = count($units);    $xs = array();    
    foreach (array_reverse($list) as $x) {        
    $l = count($xs);        
    if ($x != "0" || !($l % 4))            
    $n = ($x == '0' ? '' : $x) . ($units[($l - 1) % $ul]);        
    else
            $n = is_numeric($xs[0][0]) ? $x : '';
        array_unshift($xs, $n);
    }    
    return $xs;
}

bool is_numeric ( mixed $var )