Porting DLL import from c# to c++

Question

This is how I use/import the DLL using c#. How do I do it on c++ project?

[DllImport(@".\x64\something.dll", EntryPoint = "somthng", CharSet = CharSet.Unicode)]
static extern int somthng(string input);

Answer 1

Provided that you do not have the development header and lib files available for the DLL and you need to dynamically load the DLL into your C++ project, then you can do the following.

Define a function pointer (equivalent to your extern declaration):

typedef int FnSomeFunction(const char* input);

Load the library (I'm using LoadLibraryA here to load an ansi-named DLL, this depends on your C++ project). The DLL must be in the search path, i.e. in the same path as the executable):

HMODULE hModule = LoadLibraryA("something.dll");

Check that the module is successfully loaded:

if (hModule == nullptr)
    throw std::runtime_error("Lib not loaded");

Get the function entry point from the library:

FnSomething* fnSomething = (FnSomeFunction*)GetProcAddress(hModule, "somthng");

Call the function:

(*fnSomething)("some text");

Free the library when no longer needed:

FreeLibrary(hModule);