name mangling problem

[Jaco Naude]

Hi,

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

Thanks
Jaco

[daniel]

On Jul 23, 1:35*pm, Jaco Naude <naude.j...@gma il.comwrote:

Hi,

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
* * void Py_Initialize(v oid);

}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

Thanks
Jaco

You could change your C code file extension from .c to .cpp.
But this is not very practical.

Daniel.

[Ian Collins]

Jaco Naude wrote:

Hi,

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

That's the standard way of informing the C++ compiler functions have C
linkage.

--
Ian Collins.

[Pascal J. Bourguignon]

Jaco Naude <na********@gma il.comwrites:

Hi,

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

Yes:

#define C(X) extern "C" { X; }

C(void Py_Initialize(v oid))
C(void Py_Middlize(voi d))
C(void Py_Terminalize( void))

Assuming typing 'C( )' is easier than typing 'extern "C"{ }'...

--
__Pascal Bourguignon__

[Pete Becker]

On 2008-07-23 06:35:00 -0400, Jaco Naude <na********@gma il.comsaid:

>
I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker).

Last time I looked, VC++ did mangle names when compiling C code. It
sticks an underscore on the front.

When I try to use
any of the functions from the DLL, VC++ mangles these names

Well, it mangles them differently from the way they're mangled when
they're compiled as C code.

(or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

No, that's what extern "C" is for.

Note that this problem really has nothing to do with the use of DLLs,
except that that's where you happened to notice it. It comes up
whenever you need to link C code with C++ code. You have to tell the
compiler that those things were compiled as C so that it can generate
code with the correct calling convention (which can include more than
just changing how the names are mangled).

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

[Jaco Naude]

On Jul 23, 1:00*pm, Pete Becker <p...@versatile coding.comwrote :

On 2008-07-23 06:35:00 -0400, Jaco Naude <naude.j...@gma il.comsaid:

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker).

Last time I looked, VC++ did mangle names when compiling C code. It
sticks an underscore on the front.

*When I try to use
any of the functions from the DLL, VC++ mangles these names

Well, it mangles them differently from the way they're mangled when
they're compiled as C code.

*(or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
* * void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

No, that's what extern "C" is for.

Note that this problem really has nothing to do with the use of DLLs,
except that that's where you happened to notice it. It comes up
whenever you need to link C code with C++ code. You have to tell the
compiler that those things were compiled as C so that it can generate
code with the correct calling convention (which can include more than
just changing how the names are mangled).

--
* Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

Thanks for all the replies. Seems like thats the way to do it. I'll go
with the #define C(X) extern "C" { X; } option for now.

Thanks again.

[James Kanze]

On Jul 23, 12:53 pm, p...@informatim ago.com (Pascal J. Bourguignon)
wrote:

Jaco Naude <naude.j...@gma il.comwrites:

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
void Py_Initialize(v oid);
}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

Yes:

#define C(X) extern "C" { X; }

C(void Py_Initialize(v oid))
C(void Py_Middlize(voi d))
C(void Py_Terminalize( void))

Assuming typing 'C( )' is easier than typing 'extern "C"{ }'...

That is, quite frankly, horrible. And what happens if you use C
as a name somewhere? Not to mention that the person reading the
code will have no idea what is going on.

With any decent editor, you can set up an abbreviation so that
you just have to type C to get your extern "C", if it is really
typing which is bothering you. (Although seriously, how long
does it take to type `extern "C"?) More generally, however, the
usual solution is to define an extern "C" block for the entire
library, e.g.:

#ifdef __cplusplus
extern "C" {
#endif
void Py_Initialize( void ) ;
void Py_Middlize( void ) ;
// ...
#ifdef __cplusplus
}
#endif

(I don't normally approve of #ifdef, but this is one of those
cases where it is so ubiquious, any other solution would cause
the reader to wonder why it wasn't done this way.)

--
James Kanze (GABI Software) email:ja******* **@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[Greg Comeau]

In article <e6************ *************** *******@y38g200 0hsy.googlegrou ps.com>,
Jaco Naude <na********@gma il.comwrote:

>Thanks for all the replies. Seems like thats the way to do it. I'll go
with the #define C(X) extern "C" { X; } option for now.

If I has no compelling reason to do so, I would not use a macro,
and probably not one named C however appropriate that may seem,
to establish extern "C", but that's just me. It implies a non-C too
(or at least an empty C(X), and I think I'd rather prefer to use
a more traditional "co-ed header" file ala the discussion found at
http://www.comeaucomputing.com/techtalk/#externC ).
--
Greg Comeau / 4.3.10.1 with C++0xisms now in beta!
Comeau C/C++ ONLINE == http://www.comeaucomputing.com/tryitout
World Class Compilers: Breathtaking C++, Amazing C99, Fabulous C90.
Comeau C/C++ with Dinkumware's Libraries... Have you tried it?

[murat.dogancay]

On 23 Temmuz, 13:35, Jaco Naude <naude.j...@gma il.comwrote:

Hi,

I am running into a problem where I am trying to import C DLL into a
Visual C++ 2008 application. The functions in the C DLL are obviously
not name mangled (verified using Dependency Walker). When I try to use
any of the functions from the DLL, VC++ mangles these names (or so it
looks like) and complains that it can't link to mangled versions of
the function names. To avoid this I've figured that I need to declare
the functions I would like to use from the DLL as follows:

extern "C"
{
* * void Py_Initialize(v oid);

}

Is there any easier way of doing this than to declare all the
functions in the DLL using extern "C"?

Thanks
Jaco

Change "Project options" --"Configurat ion Properties" --C/C++ -->
Advanced --Compile as
to "Compile as C Code (/TC)" and remove the " Extern "C" "
declarations
thats all folks ! ;)
No any other changes required...
_______________ ___
http://www.invenoo.com

[ian-news]

On Jul 23, 11:36 pm, Jaco Naude <naude.j...@gma il.comwrote:

>
Thanks for all the replies. Seems like thats the way to do it. I'll go
with the #define C(X) extern "C" { X; } option for now.

That's the worst possible solution.

Don't forget you can put multiple prototypes inside a single extern
"C" {} block, so you only have to type it once rather than every time
for that horrible macro. That's how system headers are shared between
C and C++.

Ian.