Lata: Have you used these? Any experience you can share in terms of how well the conversion is done, what features are covered and not covered, etc?

Joachim: That is very simplistic, isn't it? What happens to inheritance, I/O redirection, friends classes/methods, method overloading, etc?

If you want to fully "emulate" C++ in C, you primarily need to emulate polymorphism; overloading, friends, etc. are "syntactic sugar" which provides encapsulation, etc., which is important, but has no functional impact (Operator overloading is a problem, though).

Polymorphism with virtual methods you can emulate by having a jump table (vtable) in your struct. Each class with virtual methods or a constructor needs a vtable to determine which functions to call. Also, a "super" reference to the parent's vtable is helpful.

So a very simple example with a "parent" and "child" class would be like this:

struct vtable{

void (*method_a)(struct parent_class* this);

int (*method_b)(struct parent_class* this,int);

void (*destructor)(struct parent_class* this);

};

struct vtable vtable_parent = {

&parent_method_a,

&parent_method_b.

&parent_destructor

};

struct vtable vtable_child = {

&child_method_a,

&child_method_b,

&child_destructor

};

struct parent_class{

struct vtable* _vtable;

....

}

struct parent_class* parent_class_new(){

struct parent_class* new_this = malloc(sizeof...);

new_this->_vtable = &vtable_parent;

....

}

Things to consider:

- the vtable can grow, when classes further down the class tree add virtual methods

- you needs lots of casts between the various pointer types (parent / child types)

Generally: This works, but is a mess. I'd strongly discourage this. It's a hack.

Originally C++ was implemented on many platforms using a preprocessor called C Front. It converted the C++ to C code and then fed the result to a C compiler. If you can find a working example of C front then you're home.

I read some time ago that Bjorn Stroustrup denied that C front was ever used extensively. I was at Bell Labs in 1996 and we did quite a large project on HP-UX using C front to convert C++ code we wrote to C and then object code of course.

....JW