Re: How to use a float value with either GLYPH_DEBUG or NSTRACE

[Noam Postavsky]

On Mon, Aug 21, 2017 at 4:51 PM, Keith David Bershatsky <address@hidden> wrote:
> Thank you, Alan:
>
> I had erroneously assumed that `%f` was only for adding/removing decimal 
> places or rounding, rather than to show the approximate value of a `double` 
> in this context.
>
> I ran a few tests and am guessing that `%f` uses six (6) decimal places.  I 
> understand that %f can be used to increase/decrease the number of decimal 
> places.  However, this leaves me guessing exactly what the double looks like. 
>  If the double is exactly 1.0, then it would be nice to see the same thing 
> rather than 1.000000.  If the double is several decimal places, then I'd like 
> to see the whole thing.
>
> Then again, it is possible that the snippet in the opening thread is 
> producing a double of exactly six (6) decimal places, but I do not know for 
> sure if that is the case.
>
> So the `%f` solution give me 99% of what I was looking for, which is 
> certainly sufficient to handle this particular issue.  If you or anyone else 
> have a way to print the exact value of whatever the double is (without 
> adding/removing decimal places), an additional approach would be appreciated.

I think `%.20g' should give you that (the max precision of double is
about 17 decimal digits), although I would imagine that "the whole
thing" is usually more than is really useful.

https://www.gnu.org/software/libc/manual/html_node/Floating_002dPoint-Conversions.html