PHP自动转换字符集 支持数组转换

/**
 * 自动转换字符集 支持数组转换
 */
function auto_charset($fContents, $from='gbk', $to='utf-8') {
    $from = strtoupper($from) == 'UTF8' ? 'utf-8' : $from;
    $to = strtoupper($to) == 'UTF8' ? 'utf-8' : $to;
    if (strtoupper($from) === strtoupper($to) || empty($fContents) || (is_scalar($fContents) && !is_string($fContents))) {
        //如果编码相同或者非字符串标量则不转换
        return $fContents;
    }
    if (is_string($fContents)) {
        if (function_exists('mb_convert_encoding')) {
            return mb_convert_encoding($fContents, $to, $from);
        } elseif (function_exists('iconv')) {
            return iconv($from, $to, $fContents);
        } else {
            return $fContents;
        }
    } elseif (is_array($fContents)) {
        foreach ($fContents as $key => $val) {
            $_key = auto_charset($key, $from, $to);
            $fContents[$_key] = auto_charset($val, $from, $to);
            if ($key != $_key)
                unset($fContents[$key]);
        }
        return $fContents;
    }
    else {
        return $fContents;
    }
}