Suffix allowed on expressions?

[dspfun]

Hi!

Are suffixes allowed on expressions?

For example, is the following allowed:

#define SECONDS_PER_YEA R (60 * 60 * 365) UL

I found this in a C test at http://www.embedded.com/2000/0005/0005feat2.htm
,
however, I am not able to compile when using this macro (or just the
expression "a = (60 * 60 * 365) UL;").

Where in the standard does it say that it is allowed/not allowed?

It would also be interesting to hear if there are any faults in the
other questions and answers in the test.

BRs!

[Ben Pfaff]

dspfun <ds****@hotmail .comwrites:

How about question 7, is it correct (referring to the test in the link
at the top of the thread)? :

int const * a const;

This is probably a typo for:
int const *const a;
although I would write such a declaration as, equivalently:
const int *const a;
--
"If I've told you once, I've told you LLONG_MAX times not to
exaggerate."
--Jack Klein

[Walter Roberson]

In article <71************ *************** *******@5g2000h sg.googlegroups .com>,
dspfun <ds****@hotmail .comwrote:

>Could you give a pointer to where in the standard it says that an
integer (constant) can be typecasted to a pointer and the result is
implementati on dependent?

C89 3.3.4 Cast Operators

An abitrary integer may be converted to a pointer. The result
is implementation-defined. [45]
{footnote} [45] The mapping functions for converting a pointer to
an integer or an integer to a pointer are intended to be
consistent with the addressing structure of the execution
environment.

--
"Any sufficiently advanced bug is indistinguishab le from a feature."
-- Rich Kulawiec

[dspfun]

On 4 Jan, 00:41, [e-mail] c-cnrc.gc.ca (Walter Roberson) wrote:

In article <7146c56f-be16-4c06-9a59-1a142d154...@5g 2000hsg.googleg roups.com>,

dspfun *<dsp...@hotmai l.comwrote:

Could you give a pointer to where in the standard it says that an
integer (constant) can be typecasted to a pointer and the result is
implementation dependent?

C89 3.3.4 Cast Operators

* An abitrary integer may be converted to a pointer. The result
* is implementation-defined. [45]

* {footnote} [45] The mapping functions for converting a pointer to
* an integer or an integer to a pointer are intended to be
* consistent with the addressing structure of the execution
* environment.

--
* *"Any sufficiently advanced bug is indistinguishab le from a feature."
* *-- Rich Kulawiec

Thank you, is the same valid for C99?

[Ben Pfaff]

dspfun <ds****@hotmail .comwrites:

A more obscure approach is:
*(int * const)(0x67a9) = 0xaa55;

It's *extremely* obscure why one would give an rvalue a const
type.
--
int main(void){char p[]="ABCDEFGHIJKLM NOPQRSTUVWXYZab cdefghijklmnopq rstuvwxyz.\
\n",*q="kl BIcNBFr.NKEzjwC IxNJC";int i=sizeof p/2;char *strchr();int putchar(\
);while(*q){i+= strchr(p,*q++)-p;if(i>=(int)si zeof p)i-=sizeof p-1;putchar(p[i]\
);}return 0;}

[CBFalconer]

dspfun wrote:

>

.... snip ...

>
Could you give a pointer to where in the standard it says that an
integer (constant) can be typecasted to a pointer and the result
is implementation dependent?

You can answer this sort of question more easily yourself, with a
text version of the C standard and grep. grep is available
everywhere. For the text version I suggest N869_txt.bz2, which is
a bzip2 compressed version of N869, and is available at:

<http://cbfalconer.home .att.net/download/>

--
Chuck F (cbfalconer at maineline dot net)
<http://cbfalconer.home .att.net>
Try the download section.

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

[CBFalconer]

Keith Thompson wrote:

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

>dspfun wrote:

>>>

... snip ...

>>>
Could you give a pointer to where in the standard it says that an
integer (constant) can be typecasted to a pointer and the result
is implementation dependent?

You can answer this sort of question more easily yourself, with a
text version of the C standard and grep. grep is available
everywhere. For the text version I suggest N869_txt.bz2, which is
a bzip2 compressed version of N869, and is available at:

<http://cbfalconer.home .att.net/download/>

n1256.pdf, available at
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf>,
is more current. It's PDF rather than plain text, which may or may
not be a problem.

I'm not convinced that a simple grep would be useful in this case.
For example, the word "typecast" appears nowhere in the standard.
What would you grep for?

For example, I just entered:

grep -n cast \stds\n869.txt | less

and got a set of roughly 60 lines. This took all of 2 seconds. It
shouldn't take much to hide that output and just save the line
numbers, which can then be used to illuminate all the areas of
interest.

--
Chuck F (cbfalconer at maineline dot net)
<http://cbfalconer.home .att.net>
Try the download section.

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

[Mark McIntyre]

CBFalconer wrote:

Keith Thompson wrote:

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

I'm not convinced that a simple grep would be useful in this case.
For example, the word "typecast" appears nowhere in the standard.
What would you grep for?

For example, I just entered:

grep -n cast \stds\n869.txt | less

and got a set of roughly 60 lines.

Yeah, but the OP is under the mistaken impression that "typecastin g" has
something to do with C, rather than with Hollywood. :-(

It would probably have been useful to have advised him that the word he
was searching for was 'convert'.
--
Mark McIntyre

CLC FAQ <http://c-faq.com/>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt >

[Army1987]

dspfun wrote:

A more obscure approach is:
*(int * const)(0x67a9) = 0xaa55;

The most obscure thing is what the `const` is for. A cast doesn't yield a
lvalue, so it's irrelevant whether it's const. Do you usually end the body
of main with `return (const int)0;`?

--
Army1987 (Replace "NOSPAM" with "email")

[dspfun]

On 4 Jan, 01:46, Ben Pfaff <[e-mail] rd.eduwrote:

dspfun <dsp...@hotmail .comwrites:

A more obscure approach is:
*(int * const)(0x67a9) = 0xaa55;

It's *extremely* obscure why one would give an rvalue a const
type.

Can you explain what you mean?

Isn't 0xaa55 the rvalue, 0xaa55 is an integer constant, what is the
obscure thing about that?

[Ben Pfaff]

dspfun <ds****@hotmail .comwrites:

On 4 Jan, 01:46, Ben Pfaff <[e-mail] rd.eduwrote:

>dspfun <dsp...@hotmail .comwrites:

A more obscure approach is:
*(int * const)(0x67a9) = 0xaa55;

It's *extremely* obscure why one would give an rvalue a const
type.

Can you explain what you mean?

"const" is attached to a type to make objects of that type
non-modifiable. But the result of a cast is never modifiable,
because it is not an lvalue. So the "const" keyword here is
useless.
--
char a[]="\n .CJacehknorstu" ;int putchar(int);in t main(void){unsi gned long b[]
={0x67dffdff,0x 9aa9aa6a,0xa77f fda9,0x7da6aa6a ,0xa67f6aaa,0xa a9aa9f6,0x11f6} ,*p
=b,i=24;for(;p+ =!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)bre ak;else default:continu e;if(0)case 1:putchar(a[i&15]);break;}}}