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

[Noam Postavsky <npostavs@users.sourceforge.net>]

On Mon, Aug 21, 2017 at 4:51 PM, Keith David Bershatsky <esq@lawlist.com> 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