Re: Acquiring UTF-8 string length

From:
=?Utf-8?B?Q29kZXIgR3V5?= <CoderGuy@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 2 Apr 2007 01:22:00 -0700
Message-ID:
<BBA19C58-EC4C-408C-9D09-94154489DC20@microsoft.com>
"Ulrich Eckhardt" wrote:

count of code points = 6, obtained by strlen()


Wrong. strlen() only returns the number of chars up to the first NUL char.
The number of codepoints is four, plus the terminating NUL.


Just tested: the returned length is six (6) characters. I am looking right
at Microsoft's implementation of CRT's strlen and it doesn't do any character
validation of code points, it simply reports the number of 1-byte blocks up
to the nil.

// "I{heart}NY"
char str[] = { 0x49, 0xE2, 0x99, 0xA5, 0x4E, 0x59, 0x00 };

// len becomes 6
size_t len = strlen(str);

// len becomes 6
HRESULT hr = StringCchLengthA(
    str,
    sizeof(str),
    &len);

For fixed-width character sets (Ansi) this makes sense, but I just want one
that supports variable-length character sets, which includes UTF-8 and
UTF-16. The only way I've been able to do this is call CharNextExA in a
loop, but I haven't sufficiently tested and it doesn't provide all the
information I want. I'll take a look at the ICU you referenced since I am
not looking forward to rolling my own encoder/decoder.

Thanks

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