Question

I just bought a device that comes with a dll file. I want to use Visual C++ to program the device. How do I load the .dll file into my project?

Answer 1

A DLL is a library file that contains compiled program logic, just like an EXE. You can’t execute it alone, but like an EXE file you can’t just ‘load’ it into your project either.

You will need to use functions like Load Library to load the library, and then GetProcAddress to find a function you want to call.

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Edit:

After you clarified your question in the comments you are trying to write a windows program instead of a program you run on your device.

I wrote some sample code to show you how to start:

#include <windows.h>     // This is a windows header file. The functions I mentioned above are declared here
#include "mpusbapi.h"    // This is the header file supplied. It declares the function prototypes that are defined in the DLL

int main(int argc, char* argv)
{
    // Try to load the library
    HMODULE mpbusDLL = NULL;
    mpbusDLL = LoadLibrary(L"mpusbapi.dll");

    if (mpbusDLL != NULL) {
        // If the library could be loaded, then load the functions using GetProcAddress()

        // Load the function 'MPUSBOpen' from the DLL
        MPUSBOpen = (HANDLE(*)(DWORD, PCHAR, PCHAR, DWORD, DWORD)) GetProcAddress(mpbusDLL, "_MPUSBOpen"); 

        ...
        MPUSBOpen(...);
    }
}

This C code will load your libary and then attempt to load the function MPUSBOpen, which is implemented in your DLL.
You will need to load the other functions defined in your header file the same way (at least if you want to use them).