reply the answer

[guthena]

Can we write a C programe with out a semicolon ? printing HELLOWORLD !

[Peter 'Shaggy' Haywood]

Groovy hepcat Keith Thompson was jivin' on Fri, 06 Jul 2007 08:11:16
-0700 in comp.lang.c.
Re: reply the answer's a cool scene! Dig it!

>ph******@alpha link.com.au.NO. SPAM (Peter 'Shaggy' Haywood) writes:
[...]

> Yes, I think you're right. I was confusing what C90 says about
non-void functions without a return statement (basically, the above)
with what C99 says (that it's not allowed). The code in question was
C90 conforming after all, I guess. And I stand, once again, corrected.

Where does C99 say that a non-void function without a return statement
is not allowed? The closest thing I can find is C99 6.9.1p12:

If the } that terminates a function is reached, and the value of
the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just don't
know anymore.

>Note that the behavior is undefined only if the caller actually
attempts to uses the result.

Also, C99 6.8.6.4 says:

A return statement with an expression shall not appear in a
function whose return type is void. A return statement without an
expression shall only appear in a function whose return type is
void.

That's a constraint, but it says nothing about missing return
statements.

Perhaps I just need to stop posting nonsense and re-read the damn
thing (the standard... or at least n1124).

--

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http://alphalink.com.au/~phaywood/
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[Keith Thompson]

ph******@alphal ink.com.au.NO.S PAM (Peter 'Shaggy' Haywood) writes:

Groovy hepcat Keith Thompson was jivin' on Fri, 06 Jul 2007 08:11:16
-0700 in comp.lang.c.
Re: reply the answer's a cool scene! Dig it!

>>ph******@alph alink.com.au.NO .SPAM (Peter 'Shaggy' Haywood) writes:
[...]

>> Yes, I think you're right. I was confusing what C90 says about
non-void functions without a return statement (basically, the above)
with what C99 says (that it's not allowed). The code in question was
C90 conforming after all, I guess. And I stand, once again, corrected.

Where does C99 say that a non-void function without a return statement
is not allowed? The closest thing I can find is C99 6.9.1p12:

If the } that terminates a function is reached, and the value of
the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just don't
know anymore.

[...]

One possible source of confusion is a change in C99.

C90 6.6.6.4 says:

Constraints

A return statement with an expression shall not appear in a
function whose return type is void.

C99 6.8.6.4 says:

Constraints

A return statement with an expression shall not appear in a
function whose return type is void. A return statement without an
expression shall only appear in a function whose return type is
void.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[CBFalconer]

Peter 'Shaggy' Haywood wrote:

Groovy hepcat Keith Thompson wrote:

.... snip ...

>

>Where does C99 say that a non-void function without a return
statement is not allowed? The closest thing I can find is C99
6.9.1p12:

If the } that terminates a function is reached, and the value
of the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just
don't know anymore.

You just quoted it. Undefined behaviour is not quite usable.

--
<http://www.cs.auckland .ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfoc us.com/columnists/423>
<http://www.aaxnet.com/editor/edit043.html>
cbfalconer at maineline dot net

--
Posted via a free Usenet account from http://www.teranews.com

[Richard Heathfield]

CBFalconer said:

Peter 'Shaggy' Haywood wrote:

>Groovy hepcat Keith Thompson wrote:

... snip ...

>>

>>Where does C99 say that a non-void function without a return
statement is not allowed? The closest thing I can find is C99
6.9.1p12:

If the } that terminates a function is reached, and the value
of the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just
don't know anymore.

You just quoted it. Undefined behaviour is not quite usable.

Nonsense. It's just not *universally* usable. The following function
exhibits undefined behaviour:

void printat(const char *s, unsigned char attr, int x, int y)
{
unsigned char *base = (unsigned char *)0xB8000000UL;
base += 160 * y;
base += 2 * x;
while(*s != '\0')
{
*base++ = *s++;
*base++ = attr;
}
}

And yet I have *used* such a function[1] in several programs, where it
turned out to be not only *usable* but also highly *useful*, even
though it invokes undefined behaviour and even though it is not
portable (and yes, even under MS-DOS, there are systems where it can
fail). And it's lightning-quick, too.

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[Flash Gordon]

CBFalconer wrote, On 10/07/07 21:48:

Peter 'Shaggy' Haywood wrote:

>Groovy hepcat Keith Thompson wrote:

... snip ...

>>Where does C99 say that a non-void function without a return
statement is not allowed? The closest thing I can find is C99
6.9.1p12:

If the } that terminates a function is reached, and the value
of the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just
don't know anymore.

You just quoted it. Undefined behaviour is not quite usable.

The behaviour is only undefined if the value is used. The following is
perfectly legal (requires no diagnostic and does not invoke UB):

#include <stdio.h>

int sily(void)
{
puts("Hello");
}

int main(void)
{
sily();
return 0;
}

gcc will give a warning (or even error) if poked hard enough, but with
only the options to ensure full compliance to a C standard and no extra
warnings (or errors) it will produce no diagnostic.
--
Flash Gordon

[Keith Thompson]

CBFalconer <cb********@yah oo.comwrites:

Peter 'Shaggy' Haywood wrote:

>Groovy hepcat Keith Thompson wrote:

... snip ...

>>

>>Where does C99 say that a non-void function without a return
statement is not allowed? The closest thing I can find is C99
6.9.1p12:

If the } that terminates a function is reached, and the value
of the function call is used by the caller, the behavior is
undefined.

Now I'm confused. Where did I read that it's not allowed, then?
Hell, maybe it was in a parallel universe or something. I just
don't know anymore.

You just quoted it. Undefined behaviour is not quite usable.

There's a huge difference between "not quite usable" and "not
allowed".

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"