问题
I just wonder whether 0xFFFF is a valid Unicode character.
When I using the following code:
CStringW strTempW;
CString strTemp1;
INT_PTR nLen;
strTempW.Format(L"%c", 0xFFFF);
nLen = strTempW.GetLength();
strTemp1 += strTempW;
nLen = strTemp1.GetLength();
After executing the first codeline strTempW.Format(L”%c”, 0xFFFF), I will get strTempW of length 1, but cannot see it first character in Visual Studio watch window.
After executing the codeline strTemp1 += strTempW, I will get strTemp1 of length 0.
That is confusing to me. Is 0xFFFF taken as a valid Unicode code point or not?
回答1:
Go to the Unicode web site unicode.org/charts and enter FFFF in the box. It will give you a PDF to download (UFFF0.pdf for this character code; different files for different codes).
You'll find that U+FFFF is not a valid Unicode character:
FFFF
<not a character>
- The value FFFF is guaranteed not to be a Unicode character at all
回答2:
As stated in this great answer it is not, it is a reserved non character.
来源：https://stackoverflow.com/questions/20735405/is-0xffff-a-valid-unicode-character