Francis Glassborow wrote:

> so that is a good question
> >
> >My question: does the c / c++ standard
>=20
> note that those are two different standards.
>=20
> > tell anything about how
> >this case should be processed, or in other words: is this a bug
> >or does the standard allow this?

Both the C++ and C standards say that other directives
inside the skipped areas of conditional compilation are ignored.

16.1/6 in C++ says=20

 Each directive=92s condition is checked in order. If it=20
 evaluates to false (zero), the group that it controls is
 skipped: directives are processed only through the name
 that determines the directive in order to keep track
 of the level of nested conditionals; the rest of the=20
 directives=92 preprocessing tokens are ignored, as are the
 other preprocessing tokens in the group.

The exact same wording appears in 6.10.1/6 of the C99 standard.

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.research.att.com/~austern/csc/faq.html                ]

Hi,

I just recognized that in M$ vc #include directives are
processed before #if directives, e.g. the following code won't
work if the include file is not present:

#if 0
#include "fred.h"
#endif

as the preprocessor first tries to include fred (and then
commenting it out).

My question: does the c / c++ standard tell anything about how
this case should be processed, or in other words: is this a bug
or does the standard allow this?

--
   Johannes

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.research.att.com/~austern/csc/faq.html                ]

"Johannes Zellner" <johannes@zellner.org> wrote in message
news:slrn9qu2aj.lrv.johannes@orbital.zellner.org...
> Hi,
>
> I just recognized that in M$ vc #include directives are
> processed before #if directives, e.g. the following code won't
> work if the include file is not present:
>
> #if 0
> #include "fred.h"
> #endif
>
> as the preprocessor first tries to include fred (and then
> commenting it out).
>
> My question: does the c / c++ standard tell anything about how
> this case should be processed, or in other words: is this a bug
> or does the standard allow this?
>

The standard does specify it (I believe), and I don't believe MSVC behaves
as you suggest (I just did a simple test to prove that it doesn't).  Perhaps
there's more to your real problem than you posted here?

-cd

PS: The test: simply pase the exact lines you gave above into a file all by
themselves and try to compile it with cl.exe - you'll find that it succeeds,
regardless of the absense of fred.h.



---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.research.att.com/~austern/csc/faq.html                ]

In article <slrn9qu2aj.lrv.johannes@orbital.zellner.org>, Johannes
Zellner <johannes@zellner.org> writes
>Hi,
>
>I just recognized that in M$ vc #include directives are
>processed before #if directives, e.g. the following code won't
>work if the include file is not present:
>
>#if 0
>#include "fred.h"
>#endif
>
>as the preprocessor first tries to include fred (and then
>commenting it out).
If it actually lexically includes fred.h, it might not comment it out.
E.g. if fred.h was

#endif
#define x
#ifndef x

so that is a good question
>
>My question: does the c / c++ standard

note that those are two different standards.

> tell anything about how
>this case should be processed, or in other words: is this a bug
>or does the standard allow this?

Francis Glassborow
I offer my sympathy and prayers to all those who are suffering
as a result of the events of September 11 2001.

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.research.att.com/~austern/csc/faq.html                ]