Undefined reference problem of C + + C mixed programming

When using C + + programming, sometimes to use the third-party library, and the first party libraries is given in C, it is strange that the C file has been added to the project, the header file has been introduced, the compilation still appears

Undefined reference

The problem here, the third party C library header file is not added to the extern "C", the header file in the C file can be added as follows

#ifdef __cplusplus

extern "C" {

#endif

/* Additional declarations for C header files */

#ifdef __cplusplus

}

#endif/* End of __cplusplus */

Undefined reference problem of C + + C mixed programming