extern "C" error #2040: expected an identifier

Question

I still struggling to compile a C console application, the compiling procedure still failing with the error below:

"Main.c", line 51: error #2040: expected an identifier
  extern "C" void TreatReceivedSignal( int NoSignal ) ;
         ^
1 error detected in the compilation of "Main.c".
gmake: *** [Main.o] Error 2

below the declaration of the extern method on the C code :

extern "C" void TreatReceivedSignal( int NoSignal ) ;

I am using HP-UX aCC compiler [HP C/aC++ B3910B A.06.26], also I switched on the compilation flag -Ae to enable C99 support. Seems that the compiler cannot recognize the 'extern "C"' as C reserved word, may some other compilation flag need to be set. Any idea please that can solve this kind of issue? Thank you very much in advance. Regards

Answer 1

The extern "C" construct is a C++ specific thing, it can't be used in C. And the compiler treats your source file as a C source file since it has the extension .c.

The most common thing to do is to use the preprocessor to conditionally add this for C++ compilations:

#ifdef __cplusplus
extern "C" {
#endif

/* Standard C prototypes */

#ifdef __cplusplus
}
#endif