externc5.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

// Build don't link:
// Origin: [e-mail]

extern "C" int rand (void) throw ();

namespace std
{ 
extern "C" int rand(void) throw(); 
template <class T> void f(T a) {}
}

using namespace std;

int main()
{
  f(rand);
  f(std::rand);
  f(::rand);
}