Is it possible to import functions from a dll locally within a header file?

Question

C++ / C#

The header file declares the functions imported from the dll. Let's say lib_ff for float, lib_fd for double, etc. Is it possible to somehow limit the visibility of the first C functions. The declaration is finite in an h-file, which is not a translation unit. Is it possible to somehow undef those declarations? On the other hand, they are used from lib::f<..>.

Answer 1

You can leave only wrappers in the header file, and declare imported functions only in the cpp file with the implementation of these wrappers.
*.h:
template<> int f(float x) ;
template<> int f(double x);
*.cpp:
extern "C" int lib_ff(float x);
extern "C" int lib_fd(double x);
template<> int f(float x) { return lib_ff(x); }
template<> int f(double x) { return lib_fd(x); }