Home/ Questions/Q 728683
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-14T06:42:35+00:00

Based on this question I understand the purpose of the construct in linking C

  • 0

Based on this question I understand the purpose of the construct in linking C libraries with C++ code. Now suppose the following:

I have a ‘.so’ shared library compiled with a C++ compiler. The header has a ‘typedef stuct’ and a number of function declarations. If the header includes the extern “C” declaration…

#ifdef __cplusplus
extern "C"
{
#endif

  // typedef struct ...;
  // function decls

#ifdef __cplusplus
}
#endif

… what is the effect? Specifically I’m wondering if there are any detrimental side effects of that declaration since the shared library is compiled as C++, not C.

Is there any reason to have the extern “C” declaration in this case?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    This is important so that the compiler doesn’t name mangle. C++ uses name mangling to differentiate functions with operator overloads.

    Run “/usr/bin/nm” against a binary to see what C++ does with your function names:
    _ZSt8_DestroyIN9__gnu_cxx17__normal_iteratorIPiSt6vectorIiSaIiEEEEiEvT_S7_SaIT0_E

    extern “C” prevents that name mangling.

    IIRC, that makes it possible for program to dynamically link in symbols at run time. It’s common for “plugin” type architectures.

    • 0