Reputation: 11
Ok, so I', writting a C++ code for the MCP2221 converter. In order to use it I try to implement the .dll file. Namely mcp2221_dll_m_dotnetv4_x86.dll which can be downloaded from: https://www.microchip.com/DevelopmentTools/ProductDetails/PartNo/ADM00559
I've tried to implement it but I still cannot call the functions and I cannot find the reason why.
I use the following code:
#include "stdafx.h"
#include <windows.h>
#include <iostream>
#include <string.h>
using namespace std;
typedef string(WINAPI *MYPROC)();
int main()
{
HINSTANCE hinstLib;
BOOL fFreeResult, fRunTimeLinkSuccess = FALSE;
// Get a handle to the DLL module.
char a;
hinstLib = LoadLibrary(TEXT("mcp2221_dll_m_dotnetv4_x86.dll"));
// If the handle is valid, try to get the function address.
if (hinstLib != NULL)
{
cout << "LIB\tloaded" << endl;
MYPROC ProcAdd = (MYPROC)GetProcAddress(hinstLib, "M_Mcp2221_GetLibraryVersion");
// If the function address is valid, call the function.
if (NULL != ProcAdd)
{
cout << "FUNC\tloaded" << endl;
string s= ProcAdd();
fRunTimeLinkSuccess = TRUE;
}
else
{
cout << "FUNC\tNOT loaded" << endl;
}
// Free the DLL module.
fFreeResult = FreeLibrary(hinstLib);
}
else
{
cout << "LIB\tNOT loaded" << endl;
}
return 0;
}
The function is defined in the specification in the following way:
String^ M_Mcp2221_GetLibraryVersion()
Description: Returns the version number of the DLL Returns: String containing the library version Use Marshal.GetLastWin32Error() to determine the error code if the function fails.
I still get the LIB loaded FUNC NOT loaded output.
Could anyone tell me what I keep doing wrong? Will appreciate a lot.
Upvotes: 0
Views: 539
Reputation: 1904
Probably, you are using wrong dll and wrong function name.
You are trying to load function from dll for .Net-managed code - MCP2221_DLL(v2.2.1)\managed\MCP2221DLL-M-dotNet4\x86\mcp2221_dll_m_dotnetv4_x86.dll
. With an utility that shows functions exported from dll, I haven't found any functions that are exported from this one.
Try using unmanaged dll MCP2221_DLL(v2.2.1)\unmanaged\dll\mcp2221_dll_um_x86.dll
.
It has function _Mcp2221_GetLibraryVersion@4
Upvotes: 1