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Groups > comp.lang.c > #66198

Re: Floating point to string, and back via `%a'...

From "Chris M. Thomasson" <nospam@nospam.nospam>
Newsgroups comp.lang.c
Subject Re: Floating point to string, and back via `%a'...
Date 2015-07-22 14:01 -0700
Organization Aioe.org NNTP Server
Message-ID <mop0bg$6r8$1@speranza.aioe.org> (permalink)
References <moorva$su7$1@speranza.aioe.org> <lntwsw0vur.fsf@kst-u.example.com>

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> "Keith Thompson" wrote in message news:lntwsw0vur.fsf@kst-u.example.com...

> > "Chris M. Thomasson" <nospam@nospam.nospam> writes:
> > How in the heck can I use the `%a' format specifier in
> > conjunction with sprintf/sscanf so that I can convert a
> > floating point to a string, and back? I have some code,
> > but it does not work with `%a'. Damn!
[...]
> > http://codepad.org/yO2UisHn

> Change "%a" to "%la" in your sscanf call (and leave it as "%a" in your
> printf call).

I am now thinking about something simple that "should work" for
my application as long as I stick to a std representation of
floating point numbers.

http://codepad.org/UxAQn9oi

#include <stdio.h>

_______________________________________________________________
int
main(void)
{
    char buf[256] = { '\0' };
    double no = 1.0123456789;

    printf("no = %.10f\n\n", no);

    /* try to use custom precision `%.10lf' with sprintf/sscanf */
    {
        sprintf(buf, "%.10lf", no);

        double nc = 0.0;
        int status = sscanf(buf, "%lf", &nc);

        if (! status || status == EOF)
        {
            printf("sscanf %%lf error!\n");
        }

        printf("(%%s):buf = %s\n", buf);
        printf("(%%f):nc = %f\n\n", nc);

        printf("Hey man, why not simply use %.10lf as the public key? 
:^D\n\n", nc);
    }

    return 0;
}
_______________________________________________________________


What do you think Keith?

Even if the precision of the public key is beyond %.10, well, it
does not matter because I can use it after the "rounding"
(double=>string=>double). I will be sending the %.10 across the
wire anyway. Humm...

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Thread

Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 12:46 -0700
  Re: Floating point to string, and back via `%a'... James Kuyper <jameskuyper@verizon.net> - 2015-07-22 16:19 -0400
    Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 13:49 -0700
      Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 14:01 -0700
      Re: Floating point to string, and back via `%a'... James Kuyper <jameskuyper@verizon.net> - 2015-07-22 17:18 -0400
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:22 -0700
  Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 13:40 -0700
    Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:01 -0700
      Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 14:12 -0700
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:20 -0700
          Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:24 -0700
          Re: Floating point to string, and back via `%a'... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-22 21:30 +0000
            Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:39 -0700
          Re: Floating point to string, and back via `%a'... Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-07-22 19:49 -0600
  Re: Floating point to string, and back via `%a'... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-22 22:28 +0100
    Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 14:34 -0700
      Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 14:58 -0700
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 15:43 -0700
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 15:45 -0700
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 15:51 -0700
          Re: Floating point to string, and back via `%a'... Robert Wessel <robertwessel2@yahoo.com> - 2015-07-22 18:21 -0500
            Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 16:58 -0700
        Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 16:52 -0700
        Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 17:08 -0700
      Re: Floating point to string, and back via `%a'... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-23 00:01 +0100
        Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-22 19:40 -0700
          Re: Floating point to string, and back via `%a'... Keith Thompson <kst-u@mib.org> - 2015-07-22 22:32 -0700
          Re: Floating point to string, and back via `%a'... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-23 11:07 +0100
            Re: Floating point to string, and back via `%a'... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-23 11:25 +0100
              Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-24 11:44 -0700
            Re: Floating point to string, and back via `%a'... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-24 11:47 -0700

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