Re: code for 32/64 bit strtoul strtol strtoull strtoll

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: code for 32/64 bit strtoul strtol strtoull strtoll
Date	2015-04-02 14:30 -0700
Organization	None to speak of
Message-ID	<87pp7mgqvj.fsf@kst-u.example.com> (permalink)
References	(6 earlier) <co0i5dFq6k4U1@mid.individual.net> <jvdnhatbsgc9n3kui2s10q2a9arfk5hpgk@4ax.com> <mfglji$p0n$1@dont-email.me> <5rlphadmbkbdlauks9jmpgful56rc67n9t@4ax.com> <d5fb5a38-b9e8-480d-8f89-97531203bc07@googlegroups.com>

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Malcolm McLean <malcolm.mclean5@btinternet.com> writes:
> On Thursday, April 2, 2015 at 7:01:14 AM UTC+1, robert...@yahoo.com wrote:
>> In general C's input an output functions have many limitations and
>> quirks, the input functions being almost unusable. At least if the
>> format parsed by strto*() is the one you want, you can actually use
>> those functions in code having to deal with real-world inputs, which
>> is more than you can say for anything in the scanf family.
>>
> The printf() format string has been  big hit, imitated by numerous other languages.
> However it doesn't adapt well to Russian doll programming, because you need to 
> know the width of the integers you a re passing to it. So if we invent a new type,call 
> it index_t, we can't print out an index_t without casting it to something else, 

Yes.

> which defeats the purpose of having an index_t.

No.

You only have to do the cast when passing an index_t value to printf(),
which typically will not be a common occurrence.  Assuming index_t is an
integer type, and assuming it's signed, you can just do:

    index_t index = ...;
    printf("%jd", (intmax_t)index);

It gets slightly more complicated if you don't know the signedness of
index_t, or if you can't assume C99 support, but that can be handled.

Output code like that is typically isolated; most code that deals
with index_t objects and values doesn't have to worry about it.

Whatever purpose there is to having a distinct index_t type is not
defeated by the minor inconvenience of not having a printf format for
it.

It Would Be Nice to have type-safe output where you don't have to know
the type of something to be able to print it.  (C++'s std::cout << ...
has its advantages, but one big problem IMHO is that changing an output
format changes the state of the output stream.)

There are some things you can do with _Generic, but it's less convenient
than actual overloading.  (I express no opinion at this time on whether
adding overloading to C would be a good or bad idea.)

> The input functions are showing their age. They're Ok for low security input of
> automatically generated file, but issues such as how to represent missing data,
> Nans, signed zeros, infinities and infinitesimals, and so on aren't nailed down,
> mean that it's hard to make them really solid. There's also the irritating rule that
> newline doesn't match a newline in scant() 

Yes, input is messy.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Thread

code for 32/64 bit strtoul strtol strtoull strtoll jacob navia <jacob@jacob.remcomp.fr> - 2015-03-29 17:33 +0200
  code for 32/64 bit strtoul strtol strtoull strtoll asetofsymbols@gmail.com - 2015-03-29 09:22 -0700
    Re: code for 32/64 bit strtoul strtol strtoull strtoll Barry Schwarz <schwarzb@dqel.com> - 2015-03-29 15:12 -0700
      Re: code for 32/64 bit strtoul strtol strtoull strtoll asetofsymbols@gmail.com - 2015-03-29 23:07 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Barry Schwarz <schwarzb@dqel.com> - 2015-03-29 09:44 -0700
    Re: code for 32/64 bit strtoul strtol strtoull strtoll jacob navia <jacob@jacob.remcomp.fr> - 2015-03-29 19:05 +0200
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-29 12:15 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-03-30 02:01 +0100
    Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-29 19:48 -0700
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Barry Schwarz <schwarzb@dqel.com> - 2015-03-29 22:08 -0700
        Re: code for 32/64 bit strtoul strtol strtoull strtoll Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-03-30 12:44 +0100
          Re: code for 32/64 bit strtoul strtol strtoull strtoll Barry Schwarz <schwarzb@dqel.com> - 2015-03-30 09:04 -0700
            Re: code for 32/64 bit strtoul strtol strtoull strtoll Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-03-30 21:00 +0100
        Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-30 08:24 -0700
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Tim Rentsch <txr@alumni.caltech.edu> - 2015-03-30 07:21 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Ian Collins <ian-news@hotmail.com> - 2015-03-30 18:02 +1300
    Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-03-30 08:03 +0100
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Ian Collins <ian-news@hotmail.com> - 2015-03-30 20:33 +1300
        Re: code for 32/64 bit strtoul strtol strtoull strtoll Ian Collins <ian-news@hotmail.com> - 2015-03-30 20:35 +1300
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Tim Rentsch <txr@alumni.caltech.edu> - 2015-03-30 07:27 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-30 09:08 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-30 09:29 -0700
  Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-03-30 15:16 -0500
    Re: code for 32/64 bit strtoul strtol strtoull strtoll jacob navia <jacob@jacob.remcomp.fr> - 2015-03-31 00:15 +0200
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-03-31 01:42 -0500
    Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-03-30 23:39 +0100
      Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-03-31 01:44 -0500
        Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-03-31 13:01 +0100
          Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-31 05:13 -0700
          Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-31 08:06 -0700
            Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-31 08:26 -0700
            Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-03-31 16:40 +0100
              Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-31 09:39 -0700
              Re: code for 32/64 bit strtoul strtol strtoull strtoll Kaz Kylheku <kaz@kylheku.com> - 2015-03-31 18:22 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-03-31 19:36 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-31 12:11 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Kaz Kylheku <kaz@kylheku.com> - 2015-03-31 19:23 +0000
            Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-03-31 16:52 +0100
              Re: code for 32/64 bit strtoul strtol strtoull strtoll glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-03-31 17:54 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll raltbos@xs4all.nl (Richard Bos) - 2015-03-31 18:51 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-03-31 20:05 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll James Kuyper <jameskuyper@verizon.net> - 2015-03-31 15:18 -0400
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-03-31 20:49 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-31 13:06 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll raltbos@xs4all.nl (Richard Bos) - 2015-04-06 13:03 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-04-06 14:27 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-04-06 17:01 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-06 11:25 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll James Kuyper <jameskuyper@verizon.net> - 2015-04-06 23:34 -0400
                Re: code for 32/64 bit strtoul strtol strtoull strtoll glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-07 03:46 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll James Kuyper <jameskuyper@verizon.net> - 2015-04-08 11:05 -0400
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-08 08:31 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-03-31 19:54 +0000
                Re: code for 32/64 bit strtoul strtol strtoull strtoll James Kuyper <jameskuyper@verizon.net> - 2015-03-31 16:55 -0400
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-03-31 22:20 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-31 14:36 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-03-31 14:55 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-03-31 17:00 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-04-01 01:24 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll James Kuyper <jameskuyper@verizon.net> - 2015-03-31 23:33 -0400
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Richard Heathfield <rjh@cpax.org.uk> - 2015-04-01 04:42 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-03-31 20:26 +0100
            Re: code for 32/64 bit strtoul strtol strtoull strtoll Ian Collins <ian-news@hotmail.com> - 2015-04-01 10:33 +1300
              Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-04-01 04:33 -0500
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Bartc <bc@freeuk.com> - 2015-04-01 12:43 +0100
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-04-02 01:02 -0500
                Re: code for 32/64 bit strtoul strtol strtoull strtoll asetofsymbols@gmail.com - 2015-04-01 23:57 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-04-03 00:29 -0500
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-02 09:01 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Keith Thompson <kst-u@mib.org> - 2015-04-02 14:30 -0700
                Re: code for 32/64 bit strtoul strtol strtoull strtoll Robert Wessel <robertwessel2@yahoo.com> - 2015-04-03 00:39 -0500
                Re: code for 32/64 bit strtoul strtol strtoull strtoll glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-01 15:55 +0000

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