I'm new at programing in C/C++, and although I've looked in Microsoft's help and in other StackOverflow questions I haven't found the answer to my problem.
I am trying to call an exported function from a DLL I made in Visual Studio 2008. This DLL it's called from a VBA macro and from an user interface program made in LabWindows/CVI. It works fine with the VBA macro, however the program in LabWindows crashes when I try to load it.
I tried both, statically and dynamically calling. Here's what I have:
The function in the DLL is exported in this way, _stdcall so VBA can use it and __declspec( dllexport ) to get rid of the .def file.
__declspec( dllexport ) double * __stdcall calculos( char * String_inputs);
The input string is a really long array of chars. It's a way of passing +60 strings (each string separated by a comma ","). Then in the code they are divided by strtok using the comma (",") as reference. This is necesary as the input limit of VBA in a function is 60.
When I try to call the function statically (adding the .lib file and the header of the DLL to the project) I get the following error.
error: Undefined symbol '_calculos@4' referenced in "c:\PATH\cvibuild.PROJECTNAME\Debug\Main.obj".
The code of the static calling is the following:
double * array_out; //Pointer to array of double
array_out = calculos(STRING_INPUT);
I tried calling the function with his decorated name, but it doesn't work.
array_out = _calculos@4(STRING_INPUT);
When I checked on DependencyWalker the name of the function I get this name:
?calculos@@YGPANPAD@Z
I tried using it too on the function calling and definition without success.
What I'm doing wrong?
When I try to call the function dynamically the program crashes. The DLL, the header file and the .lib are placed in the project folder.
typedef double * (*DLLFUNC)(char*); //DLL function prototype
HINSTANCE hinstLib; //Handle to the DLL
DLLFUNC ProcAddress; //Pointer to the function
hinstLib = LoadLibrary("General.dll");
//The the pointer to the exported function and typecast it so that we can easily call it
//DLLFUNC is typedef'ed above
ProcAddress = (DLLFUNC) GetProcAddress(hinstLib, "?calculos@@YGPANPAD@Z");
//Call the function using the function pointer
double * array_out = ProcAddress(STRING_INPUT); //It crashes here
When I debug the program when it crashes I find that the commas (",") in my char * are replaced with '\0', so only the first string gets to the DLL. That may be the reason, but I just don't know why the commas (",") are replaced.
I've also tried calling it with the decorated names, without success.
ProcAddress = (DLLFUNC) GetProcAddress(hinstLib, "_calculos@4");//Error -> Dereference to null pointer
ProcAddress = (DLLFUNC) GetProcAddress(hinstLib, "calculos"); //Error -> Dereference to null pointer
