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Guido Belligoi · Guest

Hi,

I compiled 2 simple source-files with cl -c main.cpp and cl -c test.c.
test.c contains just a simple function, which is declared in test.h.
test.h is included in test.c and in main.cpp.
When I try to link the objects with link main.cpp test.c -out:prog.exe
I get the error:
"main.obj : error LNK2019: unresolved external Symbol "int __cdecl
greater(int,int)" (?greater@@YAHHH@Z), called in function _main
prog.exe : fatal error LNK1120: 1 unresolved external Symbol"

What have I to do, to be able to link those objects together?

Guido Belligoi

Ivan Vecerina · Guest

"Guido Belligoi" <DonBlech (AT) web (DOT) de> wrote in message
news:1161244159.510082.56460 (AT) b28g2000cwb (DOT) googlegroups.com...
: Hi,
:
: I compiled 2 simple source-files with cl -c main.cpp and cl -c test.c.
: test.c contains just a simple function, which is declared in test.h.
: test.h is included in test.c and in main.cpp.
: When I try to link the objects with link main.cpp test.c -out:prog.exe
: I get the error:
: "main.obj : error LNK2019: unresolved external Symbol "int __cdecl
: greater(int,int)" (?greater@@YAHHH@Z), called in function _main
: prog.exe : fatal error LNK1120: 1 unresolved external Symbol"
:
: What have I to do, to be able to link those objects together?

A: extern "C"

For headers that are to be included both from C and C++ sources,
it is common to surround all declarations with:

#ifdef __cplusplus
extern "C" {
#endif

int greater(int a, int b);

#ifdef __cplusplus
}
#endif

You could also include an originally C-only header with:
extern "C" {
#include "test.h"
}

IIRC it is also possible to declare an individual function
as extern C:

extern "C" int greater(int a, int b);

hth-Ivan
--
http://ivan.vecerina.com/contact/?subject=NG_POST <- email contact form
Brainbench MVP for C++ <> http://www.brainbench.com

Guido Belligoi · Guest

Ivan Vecerina schrieb:

a very helpfully answer!

Thank you for the fast reply - it works fine now!!!

Guido Belligoi