Using C++ library in C code

Question

Yes, this is certainly possible. You will need to write an interface layer in C++ that declares functions with extern "C":

extern "C" int foo(char *bar)
{
    return realFoo(std::string(bar));
}

Then, you will call foo() from your C module, which will pass the call on to the realFoo() function which is implemented in C++.

If you need to expose a full C++ class with data members and methods, then you may need to do more work than this simple function example.

C++ FAQ Lite: "How to mix C and C++ code".

Some gotchas are described in answers to these questions:

• [32.8] How can I pass an object of a C++ class to/from a C function?
• [32.9] Can my C function directly access data in an object of a C++ class?

Main gotcha: exceptions can not be caught in C. If there is the possibility of an exception rising in the C++ code, either write your C code or your C++ wrappers very carefully. Conversely, exception like mechanisms (i.e., longjump) in the C code (as found in various scripting languages) are not required to invoke destructors for C++ objects on the stack.

you can mix C/C++ code. If your main() function in in C++, then you just need to make sure your c functions are declared

extern "C"

If your main is C, then you are probably OK except for static variables. Any constructors with your static variables are supposed to be called before main() start. This won't happen if C is your main. I you have a lot of static variables, the best thing to do is to replace static variables with singletons.