Programs without semicolon

[subnet]

I'm not a C expert, but I've seen this topic discussed in the
newsgroup several times. What's the deal with writing such programs?
Why are they considered so interesting?

Thanks

[Joona I Palaste]

subnet <su****@katamai l.com> scribbled the following:

I'm not a C expert, but I've seen this topic discussed in the
newsgroup several times. What's the deal with writing such programs?
Why are they considered so interesting?

Beats me. Maybe some professor is handing out such assignments like
they're going out of fashion, which I certainly hope they are.

--
/-- Joona Palaste (pa*****@cc.hel sinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"'It can be easily shown that' means 'I saw a proof of this once (which I didn't
understand) which I can no longer remember'."
- A maths teacher

[Darrell Grainger]

On Tue, 11 May 2004, subnet wrote:

I'm not a C expert, but I've seen this topic discussed in the
newsgroup several times. What's the deal with writing such programs?
Why are they considered so interesting?

It is hard to do without getting creative. The idea is that you really
have to know the language and have a bit of creativity to be able to write
such a program.

The other thought is that if you can write such a program you 1) know a
lot about the language and 2) you can recall the appropriate information.

For example, everyone with a degree in Computer Science learned about
recursion. If I pose a challenge that requires recursion to solve it not
everyone will be able to figure it out even though they have all had
training on recursion. Having training is one thing. Using it effectively
is what employers are really looking for.

The truth of the matter is that many people are just good at using a
search engine or memorizing questions that people like to use in
interviews.

One other aspect of these questions is that once I know what the answer is
I can impress my friends by asking them the same question and watch them
struggle with finding the answer.

The specific challenge of writing a program that has no semicolons comes
from the fact that everyone is taught that:

int main(void)
{
return 0;
}

is a minimal program. You start with this and build from here. If this
really is the simpliest program and there is already one semicolon in it,
how do you get rid of the semicolon?

int main(void)
{
return 0
}

This will not compile. You actually have to make the code more complex to
be able to remove the semicolon.

--
Send e-mail to: darrell at cs dot toronto dot edu
Don't send e-mail to vi************@ whitehouse.gov

[Dan Pop]

In <Pi************ *************** ****@drj.pf> da*****@NOMORES PAMcs.utoronto. ca.com (Darrell Grainger) writes:

On Tue, 11 May 2004, subnet wrote:

I'm not a C expert, but I've seen this topic discussed in the
newsgroup several times. What's the deal with writing such programs?
Why are they considered so interesting?

It is hard to do without getting creative. The idea is that you really
have to know the language and have a bit of creativity to be able to write
such a program.

Not really. You know from start that your main function can't contain
any statement or declaration, except the ones of its two parameters.
There is nothing useful you can do in the declaration of argc, so your
only remaining hope is argv. After this trivial analysis, the solution
becomes obvious to anyone familiar with C99.

The C89 reasoning is a bit more complex, but still no big deal:
The only statement that doesn't require a terminating semicolon is the
empty block statement. So you can make your function call in the
controlling expression of an if or while statement that conditionally
executes an empty block statement. The while statement even allows
programming loops.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

[PlasmaDragon]

> int main(void)

{
return 0
}

This will not compile. You actually have to make the code more complex to
be able to remove the semicolon.

No, you will have to make it simpler:

int main(){}

compiles fine on GCC.

[Richard Bos]

Pl**********@ly cos.co.uk (PlasmaDragon) wrote:

int main(void)
{
return 0
}

This will not compile. You actually have to make the code more complex to
be able to remove the semicolon.

No, you will have to make it simpler:

int main(){}

compiles fine on GCC.

It compiles fine, but it returns garbage.

Richard

[Dan Pop]

In <40************ ****@news.indiv idual.net> rl*@hoekstra-uitgeverij.nl (Richard Bos) writes:

Pl**********@l ycos.co.uk (PlasmaDragon) wrote:

> int main(void)
> {
> return 0
> }
>
> This will not compile. You actually have to make the code more complex to
> be able to remove the semicolon.

No, you will have to make it simpler:

int main(){}

compiles fine on GCC.

It compiles fine, but it returns garbage.

Who says it shouldn't return garbage?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de

[PlasmaDragon]

> It compiles fine, but it returns garbage.

Richard

Returns fine for me. Here's a test program:

#include <stdio.h>
#include <stdlib.h>

int main()
{
int x;
x=system("nosem icolon");
printf("%d",x);
printf("\n\n");

system("PAUSE") ;
}

Where "nosemicolo n" is the name of your program that doesn't have a
semicolon. I always get the output 0.

[Alan Balmer]

On 12 May 2004 10:41:04 -0700, Pl**********@ly cos.co.uk (PlasmaDragon)
wrote:

It compiles fine, but it returns garbage.

Richard

Returns fine for me. Here's a test program:

#include <stdio.h>
#include <stdlib.h>

int main()
{
int x;
x=system("nosem icolon");
printf("%d",x);
printf("\n\n");

system("PAUSE") ;
}

Where "nosemicolo n" is the name of your program that doesn't have a
semicolon. I always get the output 0.

What you're printing is the return value of system, which is
implementation-defined and may or may not reflect the return value of
nosemicolon.

BTW, why

printf("%d",x);
printf("\n\n");

rather than

printf("%d\n\n" , x);

--
Al Balmer
Balmer Consulting
re************* ***********@att .net

[Arthur J. O'Dwyer]

On Wed, 12 May 2004, PlasmaDragon wrote:

[please don't snip attributions, PlasmaDragon]

It compiles fine, but it returns garbage.

Richard

Returns fine for me. Here's a test program:

<snip> I always get the output 0.

Really? Prove it!

Test programs prove nothing, by definition. Besides,
you're arguing about a stupid quirk that's easily figured
out by consulting the Standards or a relevant FAQ.

In C89/C90/C95, falling off the end of 'main' returns
an implementation-defined value to the system.
In C99, falling off the end of 'main' is exactly equivalent
to returning 0 via 'return 0;' or 'exit(0);'.

This appears to be one of those cases where the C89 bigots
and the C99 bigots are simply butting heads for the heck of
it. If you guys would just say, "This answer refers to the
standard of 1989" and "This answer refers to the standard of
1999," threads like this one simply wouldn't happen.

-Arthur