c++ cli - Why can't i see some C++ DLL ( support CLR ) in C# project ? -

i wrote simple c++ dll ( win32 ) , change properties 'common language runtime support (/clr)' -

i created new simple winform project ( c# 4.0 ) , created reference c++ project ( c++ dll ).

now can't see c++ dll in c# project - cant use , dont know why.

if have, example, unmanaged function:

bool foofunction(int firstparameter, int secondparameter); 

if want make visible managed code have wrap (as first, simple, step) managed class:

public ref class myclass abstract sealed { public:     static bool foo(int firstparameter, int secondparameter)     {         return foofunction(firstparameter, secondparameter);     } }; 

this simple exam, if have interop complex type may need wrap them all. example if have interop function accepts string have manage this. use class this:

ref class unmanagedstring sealed { public:     unmanagedstring(string^ content) : _content(content)     {          _unicodeptr = _ansiptr = intptr::zero;      }      ~unmanagedstring()     {          free();      }      operator lpwstr()     {          if (_content == nullptr)             return null;          free();          _unicodeptr = marshal::stringtohglobaluni(_content);         return reinterpret_cast<lpwstr>(_unicodeptr.topointer());     }      operator lpcstr()     {          if (_content == nullptr)             return null;          free();          _ansiptr = marshal::stringtohglobalansi(_content);         return reinterpret_cast<lpcstr>(_ansiptr.topointer());     }      virtual system::string^ tostring() override     {         return _content;     }      virtual int gethashcode() override     {         return _content->gethashcode();     }      virtual bool equals(object^ obj) override     {         return _content->equals(obj);     }  private:     intptr _unicodeptr, _ansiptr;     string^ _content;      void free()     {         if (_unicodeptr != intptr::zero)         {             marshal::freehglobal(_unicodeptr);             _unicodeptr = intptr::zero;         }          if (_ansiptr != ntptr::zero)         {             marshal::freehglobal(_ansiptr);             _ansiptr = intptr::zero;         }     } }; 

using class can call function void foo(lpcstr psztext) foo(unamangedstring(mymanagedstring)). more complex calls have , more code have write interop between them.

note: exposing 1:1 managed interface unmanaged functions make c# code harder read, suggest write true oo interface hide underlying implementation.