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Re: writing a c program to substitute text

From fred flintstone <fred@server.invalid>
Newsgroups comp.lang.c
Subject Re: writing a c program to substitute text
Date 2017-03-01 06:59 -0800
Message-ID <eho5upFjiksU1@mid.individual.net> (permalink)
References (1 earlier) <o8ul21$ip3$1@dont-email.me> <ehiij4Ffgn1U1@mid.individual.net> <87a897u6b2.fsf@bsb.me.uk> <eho0u5Fiia5U1@mid.individual.net> <o96lts$bi$1@dont-email.me>

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On 03/01/2017 06:32 AM, D. Aaron Sawyer wrote:
> On 2017.03.01 09:33, fred flintstone wrote:
>> On 02/27/2017 05:11 AM, Ben Bacarisse wrote:
>>> fred flintstone <fred@server.invalid> writes:
>>> <snip>
>>>> I need to concatenate 'toolchain3.sh' from its constituent parts and
>>>> then increment it as the filename of gptr.
>>>
>>> That's not too hard, but it's much more fiddly in C than in any
>>> scripting language I can think of.  Why do you want to do this in C?
>>> The kind of things you hint at doing elsewhere in your post are trivial
>>> in any of the many scripting languages you have available.
>>>
>>> Anyway, here's one way:
>>>
>>>      int vnum = 3;
>>>      const char *base = "toolchain", *ext = "sh", *name_fmt = "%s%d.%s";
>>>      char name1[snprintf(0, 0, name_fmt, base, vnum, ext) + 1];
>>>      int s = snprintf(name1, sizeof name1, name_fmt, base, vnum, ext);
>>>
>>> Repeat after vnum += 1;.  Whether this is suitable (it's C99) depends in
>>> part on why you using C.
>>
>> I'm having trouble with this, ben:
>>
>>   int vnum, c, i;
>>   FILE *fptr, *gptr;
>>
>>
>>
>>   vnum = 3;
>>   const char *base = "toolchain", *ext = "sh", *name_fmt = "%s%d.%s";
>>   char name1[snprintf (0, 0, name_fmt, base, vnum, ext) + 1];
>>   int s = snprintf (name1, sizeof name1, name_fmt, base, vnum, ext);
>>
>>
>>   fptr = fopen (name1, "r");
>>   if (fptr == NULL) {
>>     printf ("fopen no bueno");
>>     exit (1);
>>   }
>>   vnum += 1;
>>
>>   char name2[snprintf (0, 0, name_fmt, base, vnum, ext) + 1];
>>   int t = snprintf (name2, sizeof name1, name_fmt, base, vnum, ext);
>                                         ^--- should be 2 (name2)
> That is not a syntax error, nor a language grammar error.
> It is just a line cloning error.
> It will compile, link, and run without obvious error.
> It will some day produce wrong results.

Hmm...still stumped that I'm not getting a file created out of this:

s is 13
name1 is toolchain3.sh
t is 13
name2 is toolchain4.sh
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int
main (int argc, char *argv[])
{
   int vnum, c, i;
   FILE *fptr, *gptr;



   vnum = 3;
   const char *base = "toolchain", *ext = "sh", *name_fmt = "%s%d.%s";
   char name1[snprintf (0, 0, name_fmt, base, vnum, ext) + 1];
   int s = snprintf (name1, sizeof name1, name_fmt, base, vnum, ext);
   printf ("s is %d\n", s);
   printf ("name1 is %s\n", name1);

   fptr = fopen (name1, "r");
   if (fptr == NULL)
     {
       printf ("fopen no bueno");
       exit (1);
     }
   vnum += 1;

   char name2[snprintf (0, 0, name_fmt, base, vnum, ext) + 1];
   int t = snprintf (name2, sizeof name2, name_fmt, base, vnum, ext);
   printf ("t is %d\n", t);
   printf ("name2 is %s\n", name2);
   gptr = fopen (name2, "w");

   if (gptr == NULL)
     {
       printf ("gopen no bueno");
       exit (1);
     }

   while (1)
     {
       c = fgetc (fptr);

       if (c == EOF)
	break;
       else
	putc (c, gptr);
     }


   fclose (fptr);
   fclose (gptr);

   return 0;
}
>
>>   gptr = fopen (name2, "w");
>>
>>   if (gptr == NULL) {
>>     printf ("gopen no bueno");
>>     exit (1);
>>   }
>>>
>>> <snip>
>>> (Your posts will get more helpful replies if they are short and to the
>>> point.)
>>>
>>
>> Does the source itself announce what's wrong with it?
>
> Latent bugs are nasty.  Intermittent bugs are worse.  Good luck.

Nice catch. Thanks.
-- 
fred

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writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-26 04:14 -0800
  Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-26 04:55 -0800
  Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-26 14:28 +0100
    Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 03:58 -0800
      Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 13:11 +0000
        Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-27 13:33 +0000
          Re: writing a c program to substitute text scott@slp53.sl.home (Scott Lurndal) - 2017-02-27 17:12 +0000
            Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-27 17:59 +0000
              Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:05 +0100
              Re: writing a c program to substitute text scott@slp53.sl.home (Scott Lurndal) - 2017-02-27 18:37 +0000
                Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 11:40 -0800
        Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-02-27 16:03 +0100
        Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 05:33 -0800
          Re: writing a c program to substitute text "D. Aaron Sawyer" <aaron@110.net> - 2017-03-01 10:32 -0400
            Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 06:59 -0800
              Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-01 15:24 +0000
                Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-02 01:47 -0800
                Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 11:05 +0000
      Re: writing a c program to substitute text jt@toerring.de (Jens Thoms Toerring) - 2017-02-27 13:33 +0000
        Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:10 -0800
          Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:07 +0100
            Re: writing a c program to substitute text jt@toerring.de (Jens Thoms Toerring) - 2017-02-27 18:23 +0000
      Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 14:46 +0100
        Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 09:27 -0500
          Re: writing a c program to substitute text GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-02-27 15:28 +0100
            Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 09:38 -0500
          Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 15:44 +0100
            Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 10:36 -0500
            Re: writing a c program to substitute text Anglican <h.toms@qmul.ac.uk> - 2017-02-27 15:50 +0000
              Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 17:13 +0100
              Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 16:30 -0800
          Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:08 -0800
            Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:20 -0800
              Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:24 -0800
        Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-02-27 16:00 +0100
        Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:22 -0800
          Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:11 +0100
      Re: writing a c program to substitute text John Bode <jfbode1029@gmail.com> - 2017-02-28 15:41 -0800
        solved Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-02 01:25 -0800
          Re: solved Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-03-02 11:28 +0100
          Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 10:54 +0000
            Re: solved Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-03-02 15:28 +0100
              Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 14:51 +0000
            Re: solved Re: writing a c program to substitute text John Bode <jfbode1029@gmail.com> - 2017-03-02 14:18 -0800
              Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 23:55 +0000
                Re: solved Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-14 18:32 -0700
        Re: writing a c program to substitute text Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-17 07:04 -0700
    Re: writing a c program to substitute text jladasky@itu.edu - 2017-02-27 13:48 -0800
      Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 14:16 -0800
        Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 08:47 +0100
          Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-28 01:59 -0800
            Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 11:39 +0100
            Re: writing a c program to substitute text Richard Heathfield <rjh@cpax.org.uk> - 2017-02-28 12:03 +0000
              Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-28 13:33 +0000
                Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 14:43 +0100
                Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-28 13:59 +0000
                Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 04:26 -0800
      Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 23:29 +0100
      Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 15:10 -0800
  Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 06:42 -0800
    Re: writing a c program to substitute text Richard Heathfield <rjh@cpax.org.uk> - 2017-02-26 16:54 +0000
      [OT] "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2017-02-27 00:56 +0800
    Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-26 13:36 -0800
      Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 14:53 -0800
        Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 00:53 +0100
          Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 17:30 -0800
            Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-26 17:44 -0800
            Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 01:46 +0000
              Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 09:29 +0100
                Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 02:12 -0800
                Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 13:11 +0100
    Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 04:41 -0800
      Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 05:04 -0800
        Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 13:25 +0000
        Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:56 -0800
  Re: writing a c program to substitute text "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2017-02-27 01:00 +0800
  Re: writing a c program to substitute text "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-26 18:55 -0500
    Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-28 04:20 -0800
      Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 14:38 +0100
        Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 08:33 -0800
          Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 19:38 +0100
            Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 11:40 -0800
              Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 21:03 +0100
            Re: gcc optimization levels Noob <root@127.0.0.1> - 2017-02-28 22:55 +0100
      Re: writing a c program to substitute text "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-28 11:43 -0500
      Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 08:46 -0800

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