How to determine the size of an output buffer

[Chad]

Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {
int i=0;

for(i=0; i< 10; i++) {
printf("a \n");
}
return 0;
}
I get this....
[cdalten@localho st ~]$ ./out
a
a
a
a
a
a
a
a
a
a

BUT Now, I change the printf() to
printf("a test\n");

Now when I run
#include <stdio.h>

int main(void) {
int i=0;

for(i=0; i< 10; i++) {
printf("a test\n");
}
return 0;
}
I get....

[cdalten@localho st ~]$ ./out
a test
a test
a test
a test
a test

As you can see, only the first few lines get printed out.

Is there anyway I can determine the size of this output buffer without
restorting to trial and error to guess how large the output buffer
might be?

Chad

[Logan Shaw]

Chad wrote:

Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

It could be that stdio has a bug, but strictly speaking, if you're
not giving the system a valid C program, it doesn't have to have
correct output.

- Logan

[Peter Nilsson]

Logan Shaw <lshaw-use...@austin.r r.comwrote:

Chad wrote:

Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

Since clc wouldn't have said that about the OP's code, I'm not sure
what trouble you're saving clc from. The signature for main is not
only valid, but any conforming hosted implementation must support it.

Perhaps you were thinking of void main(void)?

--
Peter

[Peter Nilsson]

On Apr 13, 11:43 am, "Chad" <cdal...@gmail. comwrote:

Okay, let's say I have an exotic os that limits how much goes to
stdout.

Many systems allow stdout to be redirected, and many systems allow
user file limits. So, such a system isn't as exotic as you might
think.

When I go like..

#include <stdio.h>

int main(void) {
int i=0;

for(i=0; i< 10; i++) {
printf("a \n");

Note that implementations are allowed to strip trailing whitespace
from text stream lines. [In other words, behave as if you had
written printf("a\n");]

}
return 0;

}

I get this....
[cdalten@localho st ~]$ ./out
a
a
a
a
a
a
a
a
a
a

BUT Now, I change the printf() to
printf("a test\n");

Now when I run

<snip>

I get....

[cdalten@localho st ~]$ ./out
a test
a test
a test
a test
a test

As you can see, only the first few lines get printed out.

Is there anyway I can determine the size of this output buffer
without restorting to trial and error to guess how large the
output buffer might be?

No, but you can always check the return value of printf for
error (or ferror) as you can with other output functions.

--
Peter

[Chad]

On Apr 12, 7:02 pm, "Peter Nilsson" <[e-mail]. auwrote:

Logan Shaw <lshaw-use...@austin.r r.comwrote:

Chad wrote:

Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

Since clc wouldn't have said that about the OP's code, I'm not sure
what trouble you're saving clc from. The signature for main is not
only valid, but any conforming hosted implementation must support it.

Perhaps you were thinking of void main(void)?

--

Trying not to get to far off topic, here is what happens when I change
int main(void)

to

void main(void)

[cdalten@localho st ~]$ gcc --version
gcc (GCC) 4.1.1 20061011 (Red Hat 4.1.1-30)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There
is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

[cdalten@localho st ~]$ gcc -Wall out.c -o out
out.c:3: warning: return type of 'main' is not 'int'
out.c: In function 'main':
out.c:9: warning: 'return' with a value, in function returning void

[Dave Vandervies]

In article <46************ ***********@roa drunner.com>,
Logan Shaw <ls**********@a ustin.rr.comwro te:

>Chad wrote:

>Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

Uhh... what? That's a perfectly valid set of arguments for main();
one of the two that are specifically described as acceptable, in fact.

>It could be that stdio has a bug, but strictly speaking, if you're
not giving the system a valid C program, it doesn't have to have
correct output.

I don't seem to recall the OP claiming that the described behavior was
observed anywhere; he was asking about how to determine the details
given an implementation that *did* act that way.
dave
(stdio output functions are supposed to report failure, aren't they?
Don't forget to flush.)

--
Dave Vandervies dj******@csclub .uwaterloo.ca
If you write out a fully-factored grammar, this problem never occurs. [The
problem that occurs instead is that you go crazy and start mumbling thousands
of sub-rules.]) --Chris Torek in comp.lang.c

[Jack Klein]

On 12 Apr 2007 19:09:11 -0700, "Chad" <cd*****@gmail. comwrote in
comp.lang.c:

On Apr 12, 7:02 pm, "Peter Nilsson" <[e-mail]. auwrote:

Logan Shaw <lshaw-use...@austin.r r.comwrote:

Chad wrote:
Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

Since clc wouldn't have said that about the OP's code, I'm not sure
what trouble you're saving clc from. The signature for main is not
only valid, but any conforming hosted implementation must support it.

Perhaps you were thinking of void main(void)?

--

Trying not to get to far off topic, here is what happens when I change
int main(void)

to

void main(void)

[cdalten@localho st ~]$ gcc --version
gcc (GCC) 4.1.1 20061011 (Red Hat 4.1.1-30)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There
is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

[cdalten@localho st ~]$ gcc -Wall out.c -o out
out.c:3: warning: return type of 'main' is not 'int'
out.c: In function 'main':
out.c:9: warning: 'return' with a value, in function returning void

No, don't do that. Logan Shaw either had a brain fart or he doesn't
know as much about C as he thinks he does.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
comp.lang.c http://c-faq.com/
comp.lang.c++ http://www.parashift.com/c++-faq-lite/
alt.comp.lang.l earn.c-c++
http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html

[Peter Nilsson]

On Apr 13, 12:09 pm, "Chad" <cdal...@gmail. comwrote:

On Apr 12, 7:02 pm, "Peter Nilsson" <[e-mail]. auwrote:

Logan Shaw <lshaw-use...@austin.r r.comwrote:

Chad wrote:
int main(void) {
>
This being cross-posted to comp.lang.c, I'll save the c-l-c
people the trouble: it's not a valid a C program if main has
the wrong number of arguments.

Since clc wouldn't have said that about the OP's code, I'm not
sure what trouble you're saving clc from. The signature for main
is not only valid, but any conforming hosted implementation must
support it.

Perhaps you were thinking of void main(void)?

Trying not to get to far off topic, here is what happens when I
change int main(void) to void main(void)...

What happens is that you go from having a program with behaviour
defined by the C language standards, to a program with behaviour
that isn't.

http://c-faq.com/ansi/voidmain.html

--
Peter

[Logan Shaw]

Peter Nilsson wrote:

Logan Shaw <lshaw-use...@austin.r r.comwrote:

>Chad wrote:

>>Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..
#include <stdio.h>
int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

Since clc wouldn't have said that about the OP's code, I'm not sure
what trouble you're saving clc from. The signature for main is not
only valid, but any conforming hosted implementation must support it.

Well, that is embarrassing.

I could've sworn that I was told by somebody at one point that only
the other form was valid. Or maybe I misunderstood someone's statement
at some point in the past.

At any rate, I regret spreading wrong information.

On the other hand, I am glad to have found out the real story, because
I have often found it irritating thinking I had to declare arguments
when actually there was a perfectly legal alternative...

- Logan

[Martin Ambuhl]

Logan Shaw wrote:

Chad wrote:

>Okay, let's say I have an exotic os that limits how much goes to
stdout. When I go like..

#include <stdio.h>

int main(void) {

This being cross-posted to comp.lang.c, I'll save the c-l-c people
the trouble: it's not a valid a C program if main has the wrong
number of arguments.

That's true, but
int main(void) {
has the right number of arguments, being one of the two forms that a
compiler is _required_ to handle properly.
What was your point?