Is 0xFFFF a valid Unicode character?

Question

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?

Are you referring to a code point or to a character encoding? — IInspectable, Dec 23 '13 at 00:02

score 13 · Answer 1 · edited Jun 20 '20 at 09:12

13

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

edited Jun 20 '20 at 09:12

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answered Dec 23 '13 at 00:01

Jonathan Leffler

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Moreover, *all* the last two bytes in each plane are excluded. – Kerrek SB Dec 23 '13 at 00:54
Thanks, @KerrekSB. That doesn't surprise me, but I'd not validated it. I knew that U+10FFFF, the largest value in Unicode, is not a character, but I didn't want to generalize without investigating (and I was too lazy to investigate at the moment). – Jonathan Leffler Dec 23 '13 at 00:59

score 4 · Answer 2 · edited May 23 '17 at 12:19

4

As stated in this great answer it is not, it is a reserved non character.

edited May 23 '17 at 12:19

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answered Dec 23 '13 at 00:02

lwi

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Is 0xFFFF a valid Unicode character?

2 Answers2

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