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Re: Distributing C as headers.

From "Pascal J. Bourguignon" <pjb@informatimago.com>
Newsgroups comp.lang.c
Subject Re: Distributing C as headers.
Date 2019-01-28 12:21 +0100
Organization Informatimago
Message-ID <m2y375c9it.fsf@despina.home> (permalink)
References (15 earlier) <%Hr3E.90867$nC1.33629@fx04.am4> <OTr3E.154256$592.32298@fx16.am4> <87bm41vb3k.fsf@bsb.me.uk> <10t3E.125278$9A2.93679@fx09.am4> <8736pdv80w.fsf@bsb.me.uk>

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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:

> Bart <bc@freeuk.com> writes:
>
>> On 28/01/2019 01:12, Ben Bacarisse wrote:
>>> Bart <bc@freeuk.com> writes:
>>>
>>>> On 28/01/2019 00:06, Bart wrote:
>>>>> On 27/01/2019 23:51, Pascal J. Bourguignon wrote:
>>>>
>>>>>> In C, you need a lot more information to be able to use the header.
>>>>>> In Pascal, you have all the information you need:
>>>>>>
>>>>>>      var
>>>>>>         dst:string;
>>>>>>      begin
>>>>>>        string_copy(dst,'Hello World');
>>>>>>      end;
>>>>>>
>>>>>> will work without crashing.
>>>>>
>>>>> What would string_copy(dst, dst) do? What is the capacity of dst?
>>>>> (Last time I used Pascal, strings had to have a fixed length.)
>>>>
>>>> I couldn't compile your Pascal code. Do you have a real, complete
>>>> example that will run? I have Free Pascal Compiler.
>>>
>>> This is a runable example, though I have no idea if it illustrates
>>> whatever point was being made:
>>>
>>> program copystring (output);
>>> procedure string_copy(var dst : string; src : string);
>>> begin
>>>     dst := src
>>> end;
>>> var dst : string;
>>> begin
>>>     string_copy(dst, 'Hello World');
>>>     write(dst)
>>> end.
>>
>> Thanks. I think the point was that you couldn't make a Pascal program crash, as the interfaces are more robust. However if I modify your example to:
>>
>>    program copystring (output);
>>    procedure string_copy(var dst : string; src : string);
>>    begin
>>       string_copy(dst,src)
>>    end;
>>    var dst : string;
>>    begin
>>       string_copy(dst, 'Hello World');
>>       write(dst)
>>    end.
>>
>> then run via FPC it gives me:
>>
>>  Runtime error 202 at $0040142E
>>   $0040142E
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>   $00401441
>>
>> (at a wild guess, it's run out of stack). I would say that it has
>> crashed.
>
> I went and looked.  James was talking about pointers so a more direct
> example might be this:
>
> program copystring (output);
> procedure string_copy(var dst : string; src : string);
> begin
>    dst := src
> end;
> var dp : ^string;
> begin
>    string_copy(dp^, 'Hello World');
>    write(dp^)
> end.

Part of the point that you could avoid using pointer in non-C
programming languages.  There are constructs such as passing arguments
by reference, or using opaque objects (such as string) instead of bare
pointers to characters with some missing attribute such as allocated
size or length that must be passed on the side, which is propice to
errors, and ultimately crashes.


>> (Although apparently Pascal meant to write Lisp not Pascal, so it
>> might not count.)
>
> And I'm not sure that what he says counts.

-- 
__Pascal J. Bourguignon__
http://www.informatimago.com

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Thread

Distributing C as headers. Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-01-25 07:23 -0800
  Re: Distributing C as headers. Thiago Adams <thiago.adams@gmail.com> - 2019-01-25 07:31 -0800
    Re: Distributing C as headers. Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-01-25 07:33 -0800
      Re: Distributing C as headers. Mateusz Viste <mateusz@wont.tell> - 2019-01-25 15:42 +0000
      Re: Distributing C as headers. gazelle@shell.xmission.com (Kenny McCormack) - 2019-01-25 17:40 +0000
        Re: Distributing C as headers. Thiago Adams <thiago.adams@gmail.com> - 2019-01-25 09:59 -0800
          Re: Distributing C as headers. Thiago Adams <thiago.adams@gmail.com> - 2019-01-25 10:01 -0800
          Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-25 22:17 +0100
            Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-25 21:33 +0000
        Re: Distributing C as headers. Mateusz Viste <mateusz@wont.tell> - 2019-01-25 18:07 +0000
          Re: Distributing C as headers. gazelle@shell.xmission.com (Kenny McCormack) - 2019-01-25 18:46 +0000
            Re: Distributing C as headers. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-25 19:43 -0700
              Re: Distributing C as headers. Mateusz Viste <mateusz@wont.tell> - 2019-01-26 08:13 +0000
                Re: Distributing C as headers. Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-26 13:39 -0700
                Re: Distributing C as headers. Mateusz Viste <mateusz@wont.tell> - 2019-01-26 21:00 +0000
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-26 22:29 +0100
                Re: Distributing C as headers. nobody@example.org (Scott) - 2019-01-27 04:56 +0000
                Re: Distributing C as headers. Dan Purgert <dan@djph.net> - 2019-01-27 11:36 +0000
                Re: Distributing C as headers. Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-02-25 12:26 -0800
                Re: Distributing C as headers. "Jason C. McDonald" <indeliblebluepen@gmail.com> - 2019-02-28 19:52 +0000
                Re: Distributing C as headers. Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2019-02-28 15:04 -0500
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-02-28 21:40 +0100
                Re: Distributing C as headers. James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-02-28 13:57 -0800
                Re: Distributing C as headers. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-01-27 13:33 +0000
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-27 15:06 +0100
                Re: Distributing C as headers. luser droog <luser.droog@gmail.com> - 2019-01-26 13:01 -0800
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-26 22:30 +0100
                Re: Distributing C as headers. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-02-02 09:27 +0000
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-26 22:23 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-26 13:39 -0800
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-26 22:47 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-26 14:33 -0800
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-26 23:37 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-26 15:09 -0800
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-27 15:11 +0100
                Re: Distributing C as headers. James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-27 16:12 -0500
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 00:51 +0100
                Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-28 00:06 +0000
                Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-28 00:18 +0000
                Re: Distributing C as headers. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-28 01:12 +0000
                Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-28 01:35 +0000
                Re: Distributing C as headers. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-28 02:19 +0000
                Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-28 10:40 +0000
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 12:22 +0100
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 12:21 +0100
                Re: Distributing C as headers. Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-01-28 04:03 -0800
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 13:23 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-28 11:16 -0800
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 21:08 +0100
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 01:19 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-27 16:59 -0800
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-27 16:33 -0800
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 01:35 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-27 17:20 -0800
                Re: Distributing C as headers. James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-27 22:50 -0500
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 06:52 +0100
                Re: Distributing C as headers. Bart <bc@freeuk.com> - 2019-01-28 10:55 +0000
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 12:26 +0100
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 13:27 +0100
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 13:26 +0100
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 14:03 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-28 11:12 -0800
                Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-28 12:25 +0100
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 13:33 +0100
                Re: Distributing C as headers. Keith Thompson <kst-u@mib.org> - 2019-01-28 11:20 -0800
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 21:11 +0100
                Re: Distributing C as headers. scott@slp53.sl.home (Scott Lurndal) - 2019-01-28 21:12 +0000
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-28 23:06 +0100
                Re: Distributing C as headers. David Brown <david.brown@hesbynett.no> - 2019-01-27 15:02 +0100
    Re: Distributing C as headers. "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-25 17:51 +0100
    Re: Distributing C as headers. fir <profesor.fir@gmail.com> - 2019-01-25 14:28 -0800

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