C calling C++

This is an example of how you can create a C++ library with classes and how you can provide C functions for interacting with C++ objects in the library.

cube.hpp

This contains a simple C++ class called Cube:

class Cube {
public:
    explicit Cube(int side);

    int side() const;
    int volume() const;

private:
    int m_side;
};

cube.h

This contains declarations of functions with C linkage to be able to create Cube objects and call Cube member functions.

It also has a cube_t typedef which carries the object pointer. When adding more C++ classes, create one typedef for each class and also a similar set of functions to call member functions.

typedef struct { void* obj; } cube_t;

cube_t Cube_Create(int side);
int Cube_Side(cube_t c);
int Cube_Volume(cube_t c);
void Cube_Destroy(cube_t c);

cube.cpp

This contains the actual implementation of the C++ class' member functions as well as the C functions. It's used to create a common C and C++ library, libclasses.a.

Example apps main.c and main.cpp

These contains usage examples. Both programs are linked with the same library (libclasses.a).