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| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: I think this is an impossible assignment...could you help? |
| Date | 2011-09-01 23:09 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <j3phdl$7rg$1@dont-email.me> (permalink) |
| References | (1 earlier) <1br540b0oo.fsf@snowball.wb.pfeifferfamily.net> <4E5FD915.30806@verizon.net> <1bmxeoass1.fsf@snowball.wb.pfeifferfamily.net> <ln8vq7sw91.fsf@nuthaus.mib.org> <j3pcu4$grd$1@dont-email.me> |
On 09/01/2011 09:53 PM, Eric Sosman wrote:
> On 9/1/2011 7:01 PM, Keith Thompson wrote:
>> [...]
>> fgetc() cannot be written in *portable* C.
>
> #include <stdio.h>
> int fgetc(FILE *stream) {
> return getc(stream);
> }
>
> You may object that this isn't "portable" because it relies on
> the knowledge that getc() doesn't call fgetc(), knowledge that the
> implementation has but a portable user program lacks.
No, the real problem is that it just pushes the issue off to getc().
Whether fgetc() calls getc(), or vice versa, one of them actually has to
read a character from a storage device, and that's where the real
problem comes in.
> But then, no
> portable user program can implement fgetc() at all, nor strlen() nor
> sqrt() nor anything else in the Standard library: They all belong to
> the implementation, so any attempt to implement them in portable C
> is doomed from the word "Go."
The rules for reserved identifiers impose different restrictions on user
code than they do on standard library code. It is otherwise no problem
at all writing portable C code to implement things like strlen():
size_t strlen(const char *s)
{
size_t retval=0;
while(*s++)
retval++;
return retval;
}
Can you show me comparable code for an implementation of getc() that is
compatible with your fgetc() implementation above? Compatibility means
that, among other things, it can't call fgetc(). If it calls some other
standard library function to perform the read which fills the buffer,
then I'd like to see the implementation of that function too. Repeat
until you've shown the portable code which implements the actual read
itself. I'd really like to see what that looks like.
--
James Kuyper
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I think this is an impossible assignment...could you help? Jack <spamtrap@trashcan.invalid> - 2011-08-30 21:01 +0000
Re: I think this is an impossible assignment...could you help? Ian Collins <ian-news@hotmail.com> - 2011-08-31 09:18 +1200
Re: I think this is an impossible assignment...could you help? Jack <spamtrap@trashcan.invalid> - 2011-08-30 21:20 +0000
Re: I think this is an impossible assignment...could you help? Ian Collins <ian-news@hotmail.com> - 2011-08-31 10:34 +1200
Re: I think this is an impossible assignment...could you help? John Gordon <gordon@panix.com> - 2011-08-30 21:29 +0000
Re: I think this is an impossible assignment...could you help? Jack <spamtrap@trashcan.invalid> - 2011-08-30 21:43 +0000
Re: I think this is an impossible assignment...could you help? John Gordon <gordon@panix.com> - 2011-08-30 22:16 +0000
Re: I think this is an impossible assignment...could you help? William Ahern <william@wilbur.25thandClement.com> - 2011-08-30 16:26 -0700
Re: I think this is an impossible assignment...could you help? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-30 21:44 -0400
Re: I think this is an impossible assignment...could you help? John Gordon <gordon@panix.com> - 2011-08-31 02:03 +0000
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-08-31 08:56 -0700
Re: I think this is an impossible assignment...could you help? John Gordon <gordon@panix.com> - 2011-08-31 16:15 +0000
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-08-31 09:20 -0700
Re: I think this is an impossible assignment...could you help? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-31 21:15 -0400
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-08-31 22:18 -0400
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-01 15:06 +0000
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-01 15:04 +0000
Re: I think this is an impossible assignment...could you help? John Gordon <gordon@panix.com> - 2011-09-01 15:20 +0000
Re: I think this is an impossible assignment...could you help? David Thompson <dave.thompson2@verizon.net> - 2011-09-06 01:20 -0400
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-08-30 16:37 -0700
Re: I think this is an impossible assignment...could you help? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-08-31 00:51 +0100
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-08-31 13:28 +0000
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-01 15:03 +0000
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-01 08:49 -0700
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-02 07:46 +0000
Re: I think this is an impossible assignment...could you help? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-01 21:30 -0400
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-02 07:48 +0000
Re: I think this is an impossible assignment...could you help? Ian Collins <ian-news@hotmail.com> - 2011-08-31 11:58 +1200
Re: I think this is an impossible assignment...could you help? Ike Naar <ike@sverige.freeshell.org> - 2011-08-31 07:27 +0000
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-08-31 10:37 +0100
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-08-31 13:29 +0000
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-08-31 18:41 +0100
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-01 15:05 +0000
Re: I think this is an impossible assignment...could you help? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-02 01:42 -0700
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-08-31 09:15 -0700
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-08-31 18:36 +0100
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-08-31 11:44 -0700
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-01 15:05 +0000
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-01 08:51 -0700
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-09-01 17:26 +0100
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-02 07:47 +0000
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-09-02 10:56 +0100
Re: I think this is an impossible assignment...could you help? blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-09-05 20:21 +0000
Re: I think this is an impossible assignment...could you help? "Bartc" <bc@freeuk.com> - 2011-09-09 13:59 +0100
Re: I think this is an impossible assignment...could you help? "BartC" <bc@freeuk.com> - 2011-09-02 10:43 +0100
Re: I think this is an impossible assignment...could you help? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-01 12:02 -0600
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-09-01 15:12 -0400
Re: I think this is an impossible assignment...could you help? sandeep <nospam@nospam.com> - 2011-09-01 19:36 +0000
Re: I think this is an impossible assignment...could you help? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-01 14:53 -0600
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-01 16:01 -0700
Re: I think this is an impossible assignment...could you help? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-01 17:22 -0600
Re: I think this is an impossible assignment...could you help? pete <pfiland@mindspring.com> - 2011-09-01 19:39 -0400
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-01 16:39 -0700
Re: I think this is an impossible assignment...could you help? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-09-01 18:51 -0600
Re: I think this is an impossible assignment...could you help? pete <pfiland@mindspring.com> - 2011-09-01 22:27 -0400
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-09-01 22:53 -0400
Re: I think this is an impossible assignment...could you help? Kenneth Brody <kenbrody@spamcop.net> - 2011-09-02 10:45 -0400
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-09-02 11:02 -0400
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-02 08:05 -0700
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-02 08:17 -0700
Re: I think this is an impossible assignment...could you help? Willem <willem@toad.stack.nl> - 2011-09-02 15:18 +0000
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-02 08:42 -0700
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-09-01 23:21 -0400
Re: I think this is an impossible assignment...could you help? Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-01 21:53 -0400
Re: I think this is an impossible assignment...could you help? James Kuyper <jameskuyper@verizon.net> - 2011-09-01 23:09 -0400
Re: I think this is an impossible assignment...could you help? Michael Press <rubrum@pacbell.net> - 2011-09-01 21:43 -0700
Re: I think this is an impossible assignment...could you help? Keith Thompson <kst-u@mib.org> - 2011-09-02 08:32 -0700
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