Re: Converting double to widestring
On Thu, 27 Mar 2008 18:46:29 +0100, "Alf P. Steinbach" <alfps@start.no>
wrote:
* Doug Harrison [MVP]:
I know it's undocumented; I resisted the temptation to comment that while
this fact isn't mentioned explicitly, at least we're told, "This function
is deprecated because a more secure version is available; see _ecvt_s". :)
Yes, much better wrt. buffer, but AFAICS still doesn't mention anything about
multi-threading.
The temptation was to needle MSDN a bit for exhaustively documenting this
deprecation, while not doing the same for the far more important issue of
thread safety, which they've only had 15 years or so to do. I explained
what I think of the "_s" functions in this message and others:
http://groups.google.com/group/microsoft.public.vc.language/msg/efeedab00c0c9c8c
# define _CVTBUFSIZE (309+40)
Range of double 1.7E-308 ... 1.7E308, latter requires 109 digits for integer
part, 40 buf chars left, minus one for sign, one for radix point and one '\0'.
Did you write 309 as 109? Anyway, gotcha. Out of this family of functions,
I've only ever found _ecvt useful (as a simple, quick way to get the
mantissa and exponent for more elaborate formatting, not necessarily sci.
not.), and I was thinking of that. I never wondered about _CVTBUFSIZE,
because I always used things like DBL_DIG to calculate the count.
Uhm, goodie, now if they'd just care to mention sign, radix point and
terminating zero, and giving the numeric value, like "The maximum number of
digits returned by _fcvt is _CVTBUFSIZE-3, where _CVTBUFSIZE=309+40 (note: range
of double is...)", then that would have been actually useful! :-)
Then add in documentation of the format produced, and one would be almost in
documented-land! <g>
Dream on, brother. I'm afraid all we can do is submit requests to:
https://connect.microsoft.com
Here's my most recent one:
Doc Bug: _lock_file docs are misleading and erroneous
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=300428
Now that's some seriously awful documentation, and sadly, it hasn't been
touched since I posted my feedback six months (to the day!) ago. But hey,
the example used fopen_s and sprintf_s, so it must be secure! <g>
--
Doug Harrison
Visual C++ MVP