Xref:	news2.mv.net comp.os.msdos.djgpp:2649
From:	nicolas AT dsys DOT ceng DOT cea DOT fr (Eric NICOLAS)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: MikMod210 [Linking C and C++ together]
Date:	11 Apr 1996 06:54:54 GMT
Organization:	Commissariat a l'energie atomique Grenoble (France)
Lines:	62
Message-ID:	<4kiabu$evf@news.cea.fr>
References:	<199604090947 DOT FAA22372 AT delorie DOT com>
Reply-To:	nicolas AT dsys DOT ceng DOT cea DOT fr
NNTP-Posting-Host:	hudson.ceng.cea.fr
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Nick Burton <nmr AT doc DOT ntu DOT ac DOT uk> writes:
>Ok I have this great program (mikmod) which I can make and
>run fine under GNU C Ver 2.x, when its linked to my code.
>
>But when I try to link it to some of my GNU C++ Ver 2.x
>code make complains at the linking stage that it cant find
>any of the mikmod funcs?
>

Your problem is probably to link C code and C++ code together.

In C code, functions are exported using their names with an
underscore before. For example prinf is exported as _printf.

In C++, functions are exported using their names plus characters
that tell what the args are.

So if you try to link C and C++ together, that won't work because
#include files of your C code will be parsed with the C++ function
names and those names will not be found in the previously C-compiled
..o.

The solution is to tell the compiler to generate old-C names for C-code
even if the compilation is in C++ mode. Here how to do that :

Begin ALL your C-code include files with (let say myinclude.h) :

--------------
#ifndef _MYINCLUDE_H_
#define _MYINCLUDE_H_

#ifdef __cplusplus
  extern "C" {
#endif
--------------

And finish your C-code include files with :

---------------
#ifdef __cplusplus
  }
#endif

#endif
---------------

So, when you use those include files as C-code, nothing special happens, BUT
when you use those include files in C++ code, they will be delimited by
	extern "C" { ... }
So old-C function names will be generated.


Hope it helps.


-- 
Eric Nicolas <nicolas AT dsys DOT ceng DOT cea DOT fr>

Take a look to the SWORD home page :
	http://mimine.iut.univ-metz.fr/~borysgr/sword.web/home.html

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