When to use extern “C” in C++? [duplicate]

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extern “C” makes names not mangled.

It used when:

  1. We need to use some C library in C++

    extern "C" int foo(int);

  2. We need export some C++ code to C

    extern "C" int foo(int) { something; }

  3. We need an ability to resolve symbol in shared library — so we need to get rid mangling

    extern "C" int foo(int) { something; }
///
typedef int (*foo_type)(int);
foo_type f = (foo_type)dlsym(handle,"foo")

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