Thread: How to import DLL function from a separate C file

Hi there,

I am trying to create a function in a separate .C file (not the main.c) that imports the DLL functions. Below is what I have, but it doesn't compile.

//importDLL.c

Code:

#include "importDLL.h"
#include <windows.h>

void importDLL()
{
    typedef int (*importFunction)();
    importFunction impFcn;
    HINSTANCE hinstLib = LoadLibrary("someDLL.dll");
    impFcn = (importFunction)GetProcAddress(hinstLib, "impFcn");
}

//importDLL.h

Code:

void importDLL(void);

The problem is in main.c it doesn't recognize the imported DLL function "impFcn". How can I fix it?

Does it compile or doesn't it?

There must be a function with the non-mangled name impFcn in the dll you are loading or GetProcAddress() will return null. You have not given us any of the DLL code so there is no way we can tell you what is wrong.

You variable impFcn is local to your function.

Wow I cannot believe I did not see that but you are absolutely right. impFcn will go out of scope at the end of the function. Most of use were concentrating on what the function was doing instead of seeing the obvious problem of scope. Nice catch.