CODEWITHSUNDEEP
c++c
Frank Vilea
Frank Vilea

Reputation: 8487

Using C++ files in C project

Just out of curiosity: Is there a way to use C++ files in C projects? With files I mean the ability to access functions from header files and libraries and use them in your own projects for problems that have already been solved.

Upvotes: 8

Views: 4910

Answers (6)

Matt Joiner
Matt Joiner

Reputation: 118710

See also How to mix C and C++.

Upvotes: 0

chmeee
chmeee

Reputation: 3638

If you provide a C API for the C++ library, then you can use it. Simply define the C API in a separate header (you can't use headers with C++ code in C files). The ICU project does just this, it uses C++ internally, but provides both C and C++ APIs.

Upvotes: 0

Stack Overflow is garbage
Stack Overflow is garbage

Reputation: 248269

Is it an option to go the opposite way? C++ code can include C headers and link to C libraries directly (and C code can usually be compiled as C++ with few or no changes), but using C++ from C requires a bit more care.

You can't include a C++ header from a C file and expect to compile it as C.

So what you'll have to do is expose a C-compatible interface from your C++ code (a header where everything is wrapped in extern "C", and which uses no C++-specific features). If you have such a header, you can simply include it from your C code, and link to the C++ library.

Upvotes: 5

Patrick B.
Patrick B.

Reputation: 12393

If you externalize your functions, variables and struct with

extern "C" {
    int global;
}

in the header-files and with

extern "C" int global = 20;

in your C++ code, it will be usable from C-code. The same rule applies to functions.

You can even call methods with appropriate prototypes. E.g:

class C 
{
public: 
     c(int);
     int get();
};

The C-Wrapper in your .cpp could look like:

extern "C" void * createC(int i)
{
     return (void *) new C(i);
}

extern "C" int Cget(void *o)
{ 
     return ((C *)o)->get();
}

Upvotes: 5

Andrea Bergia
Andrea Bergia

Reputation: 5552

Probably the simplest thing to do is to just compile your C files with a C++ compiler. The vast majority of the code will be compatible, and you'll get the ability to use C++ headers for free.

Upvotes: 2

Oliver Charlesworth
Oliver Charlesworth

Reputation: 272762

Yes, it is possible to mix C and C++ if you're careful. The specifics will depend on what compiler, etc. you're using.

There's a whole chapter about it at the C++ FAQ: http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html.

Upvotes: 5

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