Linker error calling C-Function from Objective-C++

Question

I\'ve got a weird linker issue. I have code that looks like so:

    double given_amount = self.modelController.levelCompleteRewardAmount;
    swrve_currency_         


        

Answer 1

If you are using c function in c++ file. you should use extern "c"{}. In .h file

#ifdef __cplusplus
extern "C" {
#endif

swrve_currency_given(parameter1, parameter2, parameter3);// a c function


#ifdef __cplusplus
}
#endif  

extern "C" is meant to be recognized by a C++ compiler and to notify the compiler that the noted function is (or to be) compiled in C style.

If you're linking to a library that was compiled as C code. use

extern "C" {
  #include "c_only_header.h"
}

Take a look at When to use extern "C" in C++?

Answer 2

You may need to surround the function prototype with:

#if defined __cplusplus
extern "C" {
#endif

void swrve_currency_given (...whatever goes here...);

#if defined __cplusplus
};
#endif

That tells the compiler that it's a C function and not a C++ function.