Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #64852

Re: printf format specifier changes

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: printf format specifier changes
Date 2015-07-07 14:30 +0100
Organization A noiseless patient Spider
Message-ID <878uas5c45.fsf@bsb.me.uk> (permalink)
References <d9147e9f-77b1-435a-b037-24041fd6974a@googlegroups.com> <mnflej$8ou$1@news.albasani.net> <87egkk5lw1.fsf@bsb.me.uk> <mngi3o$uld$1@news.albasani.net>

Show all headers | View raw

BGB <cr88192@hotmail.com> writes:

> On 7/7/2015 4:59 AM, Ben Bacarisse wrote:
>> BGB <cr88192@hotmail.com> writes:
>>
>>> On 7/6/2015 11:04 AM, Rick C. Hodgin wrote:
>>>> In 2015, what suggestions would you have for changing anything about
>>>> the format specifiers used in the printf functions?
>> <snip>
>>> possible additions:
<snip>
>>> ability for numbers to have a variable number of digits following the
>>> decimal point;
>>
>> Do you mean like an automatic version of "%10.*f"?  How would the number
>> of digits be determined?
>
> I meant more like:
>   2
>   3.14159
>   6.995
>   ...
>
> where if the digits after a given point are all 0s, they are omitted.

I see.  I think it would need to be pinned down a bit more because only
two of your three examples can be represented in binary float point --
i.e. the floating point numbers closest to 3.14159000... and
6.995000... both have non-zero decimal digits eventually.  In other
words I'd want some sort of decimal rounding followed by removal of
trailing zeros, but that comes for free as the precision.  I.e. using R
as the format, double x = 6.9950000021000

  printf("%.0R",  x); // output: "7"     (same as with "%.0f")
  printf("%.3R",  x); // output: "6.995" (same as with "%.3f")
  printf("%.8R",  x); // output: "6.995"
  printf("%.9R",  x); // output: "6.995000002"
  printf("%.15R", x); // output: "6.9950000021"

<snip>
> AFAIK, '*' isn't supported by MSVC.

Unlikely, but I don't think I've ever used MSVC.
 
> then again, asking for anything much beyond C89 is asking a bit much
> of MSVC...

The use of * as a width ("%*d"), as a precision "(%6.*f") or as both
("%*.*f"), are in the old ANSI C (C89/90 whatever name you like).

-- 
Ben.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 09:04 -0700
  Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 17:50 +0100
    Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 11:34 -0700
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 19:47 +0100
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 19:53 +0100
          Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-06 11:57 -0700
      Re: printf format specifier changes "James Harris" <james.harris.1@gmail.com> - 2015-09-06 10:53 +0100
        Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-06 04:21 -0700
    Re: printf format specifier changes Richard Heathfield <rjh@cpax.org.uk> - 2015-07-06 19:44 +0100
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-06 22:14 +0100
        Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-07-06 22:43 -0500
        Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-06 23:01 -0700
          Re: printf format specifier changes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-07 06:43 +0000
          Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 10:52 +0300
            Re: printf format specifier changes Richard Heathfield <rjh@cpax.org.uk> - 2015-07-09 09:26 +0100
              Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 12:56 +0300
                Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-12 06:12 -0700
        Re: printf format specifier changes Rosario19 <Ros@invalid.invalid> - 2015-07-07 10:22 +0200
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 10:10 +0100
      Re: printf format specifier changes Philip Lantz <prl@canterey.us> - 2015-07-07 00:54 -0700
    Re: printf format specifier changes Nobody <nobody@nowhere.invalid> - 2015-07-07 15:08 +0100
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 16:12 +0100
        Re: printf format specifier changes raltbos@xs4all.nl (Richard Bos) - 2015-07-09 10:34 +0000
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 12:25 +0100
            Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 13:02 +0300
              Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-12 11:23 +0100
    Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-07 11:50 -0700
      Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-07 12:14 -0700
    Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-07 21:52 -0500
      Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-07 20:42 -0700
        Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:12 +0300
          Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-09 05:03 -0700
            Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 13:10 -0500
          Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-09 08:58 -0400
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 08:10 -0700
            Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-12 12:58 +0300
              Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-12 12:57 -0400
              Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-12 11:14 -0700
                Re: printf format specifier changes gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-12 18:26 +0000
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-08 13:09 +0100
      Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-08 08:10 -0400
        Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-08 08:12 -0500
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-08 08:38 -0700
          Re: printf format specifier changes James Kuyper <jameskuyper@verizon.net> - 2015-07-08 12:00 -0400
            Re: printf format specifier changes Les Cargill <lcargill99@comcast.com> - 2015-07-08 17:20 -0500
      Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:08 +0300
    Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-08 20:30 +0300
      Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-08 18:56 +0100
        Re: printf format specifier changes gordonb.lmwiv@burditt.org (Gordon Burditt) - 2015-07-09 11:09 -0500
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 14:05 -0500
      Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-08 11:27 -0700
        Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-08 15:07 -0500
  Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-06 23:39 -0500
    Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 10:19 +0100
      Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 07:57 -0500
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-07 14:15 +0100
          Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 14:46 +0100
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 09:37 -0500
        Re: printf format specifier changes Phil Carmody <pc+usenet@asdf.org> - 2015-07-09 11:24 +0300
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 09:55 -0500
            Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-09 11:53 -0700
              Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-09 13:48 -0700
              Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 17:01 -0500
    Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 10:59 +0100
      Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 07:48 -0500
        Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 14:30 +0100
          Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 10:05 -0500
            Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-07 23:16 +0100
              Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-07 20:29 -0500
              Re: printf format specifier changes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-08 00:43 -0700
              Re: printf format specifier changes Robert Wessel <robertwessel2@yahoo.com> - 2015-07-09 02:29 -0500
                Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-09 10:34 +0100
                Re: printf format specifier changes BGB <cr88192@hotmail.com> - 2015-07-09 09:35 -0500
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-07 08:37 -0700
            Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-07 08:45 -0700
          Re: printf format specifier changes <william@wilbur.25thandClement.com> - 2015-07-07 12:12 -0700
  Re: printf format specifier changes pooja deshpande <namitadeshpande25@gmail.com> - 2015-07-09 09:29 -0700
    Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 09:34 -0700
      Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 09:59 -0700
        Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 22:33 +0100
          Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 15:17 -0700
            Re: printf format specifier changes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-10 00:30 +0000
              Re: printf format specifier changes Reinhardt Behm <rbehm@hushmail.com> - 2015-07-10 09:17 +0800
      Re: printf format specifier changes David Kleinecke <dkleinecke@gmail.com> - 2015-07-09 10:02 -0700
        Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 10:19 -0700
      Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-09 21:50 +0100
        Re: printf format specifier changes Keith Thompson <kst-u@mib.org> - 2015-07-09 15:05 -0700
          Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:09 -0700
          Re: printf format specifier changes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-07-10 00:28 +0100
            Re: printf format specifier changes raltbos@xs4all.nl (Richard Bos) - 2015-07-13 20:39 +0000
        Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:07 -0700
          Re: printf format specifier changes Bartc <bc@freeuk.com> - 2015-07-09 23:16 +0100
            Re: printf format specifier changes "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-09 15:25 -0700

csiph-web