On 8/1/05, avinash pawar <[EMAIL PROTECTED]> wrote:
> Hello Everyone ,
>
> Can anyone of you please tell me..
>
> what does extern "C" int func(int *,foo) accomplish ?
>
When using existing C headers that already conform to ANSI C in C++
they need to be slightly modified to enable proper linkage for the
language and to ensure that C++ keywords are not used as identifiers.
This means that you can use C headers in C++ projects in the following way:
#ifdef __cplusplus
extern "C" {
#endif
...
int func(int *,foo);
...
#ifdef __cplusplus
}
#endif
Code placed between the two ifdefs is either linked as C or C++. The
__cplusplus macro is usually predefined in appropriate system headers.
To answer your question: when a routine will be called from another
language (here C is called from C++) it should be declared in C++ as
extern "C" int func(int *,foo);
The extern "C" causes the routine to have a so called 'unmangled' name
that can be refered to not only from C but also from Fortran or Cobol.
Without extern "C" the routine will get a link 'mangled' link name
like func__abc.
Regards
\Steve
--
Steve Graegert
Software Consultancy
Mobile: +49 (176) 21248869
Office: +49 (9131) 7126409
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