Are there any pitfalls when calling functions from a C library in a C++ program?

Question

I'm using a library which has both a C interface and a C++ interface in my C++ program. The C++ one is a bit immature and I must stick with the C one. I was wondering, in more general terms, is there anything specific to keep in mind when mixing C-style binary object files with a C++ project?

Answer 1

Calling C functions from C++ programs is pretty common. There is only one thing to keep in mind - use a C++ linker :) Also keep in mind that C functions cannot use exceptions, so you have to check their return values.

Edit: others have pointed out that C function declarations should be wrapped in extern "C" {...}. Usually this is already done in library header files.

Answer 2

C functions have to be declared as extern "C", if your C header files don't do this automatically, you can do it like this for the whole header:

extern "C"
{
    #include "c-library.h"
}

Otherwise, as long as you use a C++ linker for everything all will be fine :).

Answer 3

For C functions to be called from C++, they have to be declared as extern "C". Usually something like this is used in headers:

#if defined(__cplusplus)
extern "C" {
#endif

void f();
void g();

#if defined(__cplusplus)
}
#endif