Hello,

I am writing a program in C++ that uses also C sources. As this program is pretty big project and I work on it with different people I would like to hide thousands of internal functions that are defined in C source files and leave to other programmers only interfaces or wrappers written by me to those functions. Making long story short, the example defining this is given below, and a quiestion is: how to make g() and h() functions invisible to Cpp programs but to leave them visible to other C sources.

Cheader.h: defines one "usable" function for which I write a c++ wrapper

int F(int x);

Csource.c:

#include "Cheader.h"
/* helper functions */
int h(int x)  
{
   return x*x;
}

int g(int x) 
{
   return -x/x;
}

/*exported function*/
int F(int x)
{
  return h(x)+g(x);
}

My Cpp wrapper:

header:

extern "C"{
 #include "Cheader.h"
}

int Fpp(int x)
{
  return F(x);
}

Just use two different headers, one containing the internal functions and one the public API. Then make only the external API header available.

So it meant I would need to create an additional header for g() and h() functions, or to put their declarations in CHeader.h?

Correct me if I'm wrong, but if you omit h() and g() in the Cheader.h, aren't you essentially already hiding them from any other files? You are only exposing F() from the header. Other c/cpp files can't use h() nor g() because they are undeclared.

Therefore, these public/private header files are not necessary.

Make the internal functions static.

Otherwise, they're still accessible if people know the names... and also the names are available in the global space to potentially causes clashes.

Correct me if I'm wrong, but if you omit h() and g() in the Cheader.h, aren't you essentially already hiding them from any other files? You are only exposing F() from the header. Other c/cpp files can't use h() nor g() because they are undeclared.

Therefore, these public/private header files are not necessary.

Yes, but iw I want to use second function h() or g() defined somewhere else in the same manner, compiler returns an multiple declaration error

Make the internal functions static.

Otherwise, they're still accessible if people know the names... and also the names are available in the global space to potentially causes clashes.

The problem is that I cannot make them static, as the other C files use them. And the problem is that in compeletly different folder there are exactly identical declarations of functions, but they do something compeletly different

You can easily prevent name clashes when you not use stupidly short names like g and h for those internal functions(and probably also public functions) and prefix them manually with the library name to simulate namespaces in C like many librarys do.

Also as already said you can make as many as possible static and possibly reorganize some source files to facilitate this.