mixing c and c++ code in one project

[ekailan]

I have a c++ project and i have a c code I need to mix them both in one solution .....I still get errors .
I need the c code to be in one class and I need to call it from a c++ main()/
any official technique?!

[weaknessforcats]

You can mix C and C++ coded but there's a trick to it.

First, C++ has function overloading. That is, you can have muiltiple functions of the same name as long as the arguments are different.

Second, C++ uses a decorator, or mangler, to hash a functions and it's arguiments to a unique symbol. This symbol, which may look like MHG_FYYZ is tghe name of the function called by C++ functions.

Third, a C function is not mangled. So when you call a C++ function from C you use the C++ function name and not the mangled name. Since these two name are never the same you can never call the C++ function using it's C name.

Fourth, The trick: Tell the C++ compiler that the C++ function will be called from C and ot please turn off the name mangler. You lose function overloading in C++ for this function since all function names in C++ must be unique. That's why the mangler in the first place.

To do this you use extern "C" in the C++ code:

extern "C" void MyFunction(int);

in the header file and:

extern "C" void MyFunction(int)
{
   //function body
}

Note that

extern "C"

appears only in the C++ code.

Fifth, Therefore any C function called by C++ must be extern "C" in C++. Likewise, any C function calling C++ functions must be extern "C" in C++.

No changes are ever made to the C code.

[mac11]

As a follow up to weaknessforcats , there's a C++ faq section for mixing C and C++

http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html