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

[Paul Eggert]

On 08/21/2017 02:30 PM, Noam Postavsky wrote:
> I would imagine that "the whole
> thing" is usually more than is really useful.

Yes, %.20g is not what is wanted here as it will output trailing excess 
digits, e.g, it outputs 0.1 as "0.10000000000000000555". What's wanted 
is the minimum number of digits that does not lose information. You can 
use dtoastr to do that, which is what number-to-string does.

E.g., something like the following (untested) C code. Although this 
assumes CGFloat is 'double', and outputs excess precision on 32-bit 
platforms where CGFloat is 'float', it would be easy to fix that if you 
like the idea.

#include <ftoastr.h>

void
example (CGFloat value)
{
  char buf[DBL_BUFSIZE_BOUND];
  NSTRACE ("float: %s", dtoastr (buf, sizeof buf, 0, 0, value));
}