Problem in Getting Address after loading DLL in Project

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Hi,

I have created one solution in VS2003 which contain two project one is ABD.exe and another one is ABC.DLL.
DLL class is declared as

C++

class __declspec(dllexport) Class Name

In DLL class, my entry point is

C++

unsigned int Convert(string, string)

From my another project, I am trying to call ABC.dll by using below code

C++

typedef unsigned int (*EntryPointfuncPtr)(string argv_1, string argv_2);

string Lib_File = "ABC.dll";
HINSTANCE LoadMe = LoadLibrary(Lib_File.c_str());

if(LoadME != NULL)
{
  EntryPointfuncPtr LibMain = (EntryPointfuncPtr)GetProcAddress(LoadMe, "Convert");
}

if (LibMain != NULL)
{
  unsigned int nRetVal = LibMain(strIn, strOut);
}
else
{
  cout << "ERROR OCCURED" << endl;
}

I am getting an Error Message : "ERROR OCCURED". This means that LibMain is Null.

Can anyone HELP me where I went wrong.?

Posted 15-Sep-11 22:44pm

AJ83

Updated 15-Sep-11 22:55pm

v2

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Comments

Mehdi Gholam 16-Sep-11 4:49am

Is your dll file beside the exe file?
Does LoadMe have a value?

AJ83 16-Sep-11 4:52am

yes LoadMe has a Value. It is not NULL. I have checked it.

All EXE and DLL are in same location.

Richard MacCutchan 16-Sep-11 5:25am

You have not defined your function as extern but you are trying to access it as if it is. Take your function out of the class and define it correctly.

AJ83 16-Sep-11 5:29am

Richard, my "convert" function is a part of class which is calling all other function declared in the class.

Basically, I have to export class bby using LoadLibrary(). Any Help!!

CPallini 16-Sep-11 5:46am

Yes: please read the CodeProject article, I repeat the link below:
http://www.codeproject.com/KB/DLL/classesexportedusingLL.aspx

2 solutions

Solution 1

Probably the name of your function is mangled by the C++ compiler, you have to use the

C++

extern "C" {
//..
}

construct, see here[^] and here[^]to wrap your function.

Posted 15-Sep-11 22:52pm

CPallini

Comments

Mehdi Gholam 16-Sep-11 4:53am

Ah yes, my 5!

AJ83 16-Sep-11 5:01am

When I used extern "C"
{
class __declspec(dllexport) Class Name
{
};
}

It did not work though.

CPallini 16-Sep-11 5:11am

Why do you need the class? Cannot you just export the Convert function? Explicit DLL loading of C++ classes is a bit tricky (see for instance this article:
http://www.codeproject.com/KB/DLL/classesexportedusingLL.aspx
)

AJ83 16-Sep-11 5:23am

Actually my application is in C++ which contain ABD.EXE and ABC.DLL.
Now ABC.DLL, I have to call from another application DSA.EXE.

That is why I need to have class as per requirement.

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AJ83 · Accepted Answer · 2011-09-15T23:12:00

C++

Hi Pallini,

All of my function are declared in one class named as "ABC" and it's decelration is :

C++

class __declspec(dllexport) ABC
{
  public:
   Convert (string, string);
};

After you reply, i did like this:

C++

extern "C"
{
  class __declspec(dllexport) ABC
  {
    public:
     Convert (string, string);
  };
}

And rebuilt my dll but still LibMain is NULL

Any more suggestion or help?