将C库链接到C ++

Question

I have a very trivial problem including a chain of C libraries into a C++ main project. I've experience with C but it's the first time that I'm programming in C++.

The structure of the project is a single folder with inside:

• main.cpp
• Mylib_1.c
• Mylib_1.h
• Mylib_2.c
• Mylib_2.h

---

main calls -> Mylib_1.h that calls -> My_lib2.h

//main.cpp
#include "Mylib_1.h"

//Mylib_1.h
#include "Mylib_2.h"

---

main contains both Mylib_1 and Mylib_2 functions and typedef structs

Mylib_1 uses typedef structs and functions of Mylib_2

---

Everything inside each Mylib_x.h is wrapped between extern "C", like this:

#ifndef __MYLIB_X_H
#define __MYLIB_X_H

#ifdef __cplusplus
extern "C" {
#endif 

mycode         

#ifdef __cplusplus
}
#endif 

#endif

---

But when I try to compile it with eclipse kepler on Ubuntu 12.04 x64, I get:

Mylib_1.h error: Mylib_2_type_t does not name a type

main.cpp error: Mylib_2_function1 was not declared in this scope

...

Only the above sections are marked as error in eclipse, the header looks included fine.

Furthermore according to eclipse, the __cplusplus flag is false into Mylib_2.h but true into Mylib_1.h

Thinking of some eclipse error, I've tried to manually build the project via g++ (v4.6.3) but I got the same exact problem when I've tried to link the libraries .o with the main.cpp

Seems stupid but I can't figure out what could it be. Any suggestion?

Thank you

Answer 1

Have you checked that your lines

#ifndef __MYLIB_X_H
#define __MYLIB_X_H

are really different for the two files, eg _ MYLIB 1 _H and _ MYLIB 2 _H?