I don't know if there are other easy way or not.
What I know is: if you want to use functions defined in C from C++, in the C header file, you need to add some like these:
---------------------------------------------
#ifdef __cplusplus
extern "C" {
#endif
extern float YOUR_C_FUNCTIONS( );
#ifdef __cplusplus
}
#endif
------------------------------------------------
In addition, you need to link to the corresponding C++ libraries: like Cpp_4i_CF_RegABI_Runtime.a and
C++_4i_CF_RegABI_MSL.a
In this way, you don't need to enable that "Force C++" selection
Regards,
Jeff