unicode字符代码的int和char强制转换

谁能解释一下这段代码到底是怎么回事?

var letter= 'J';
char c = (char)(0x000000ff & (uint)letter);

我理解它正在获得字符的unicode表示，但是我不完全理解:

的作用

(0x000000ff & (uint)letter

0x000000ff和将字母转换为(uint)的目的是什么?是否有一种简便的方法可以实现相同的结果?

感谢

更新

好，看起来大多数人认为这是一个不好的例子，我不想包括整个类，但我想我可能会让你看到的背景。来自参考源的WebHeaderCollection:

  private static string CheckBadChars(string name, bool isHeaderValue)
    {
        if (name == null || name.Length == 0)
        {
            // emtpy name is invlaid
            if (!isHeaderValue)
            {
                throw name == null ? 
                    new ArgumentNullException("name") :
                    new ArgumentException(SR.GetString(SR.WebHeaderEmptyStringCall, "name"), "name");
            }
            // empty value is OK
            return string.Empty;
        }
        if (isHeaderValue)
        {
            // VALUE check
            // Trim spaces from both ends
            name = name.Trim(HttpTrimCharacters);
            // First, check for correctly formed multi-line value
            // Second, check for absenece of CTL characters
            int crlf = 0;
            for (int i = 0; i < name.Length; ++i)
            {
                char c = (char)(0x000000ff & (uint)name[i]);
                switch (crlf)
                {
                    case 0:
                        if (c == ''r')
                        {
                            crlf = 1;
                        }
                        else if (c == ''n')
                        {
                            // Technically this is bad HTTP.  But it would be a breaking change to throw here.
                            // Is there an exploit?
                            crlf = 2;
                        }
                        else if (c == 127 || (c < ' ' && c != ''t'))
                        {
                            throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidControlChars), "value");
                        }
                        break;
                    case 1:
                        if (c == ''n')
                        {
                            crlf = 2;
                            break;
                        }
                        throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidCRLFChars), "value");
                    case 2:
                        if (c == ' ' || c == ''t')
                        {
                            crlf = 0;
                            break;
                        }
                        throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidCRLFChars), "value");
                }
            }
            if (crlf != 0)
            {
                throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidCRLFChars), "value");
            }
        }
        else
        {
            // NAME check
            // First, check for absence of separators and spaces
            if (name.IndexOfAny(InvalidParamChars) != -1)
            {
                throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidHeaderChars), "name");
            }
            // Second, check for non CTL ASCII-7 characters (32-126)
            if (ContainsNonAsciiChars(name))
            {
                throw new ArgumentException(SR.GetString(SR.WebHeaderInvalidNonAsciiChars), "name");
            }
        }
        return name;
    }

感兴趣的位是:

char c = (char)(0x000000ff & (uint)name[i]);

var letter= (char)4200; // ၩ
char c = (char)(0x000000ff & (uint)letter); // h
// or
// char c = (char)(0x00ff & (ushort)letter);
// ushort (2-byte unsigned integer) is enough: uint is 4-byte unsigned integer