Thread: Overloaded functions and Dll(with Explicit Linking)

Hi,
I wish to export two overloaded function from a dll and then use them in a client program which access the dll through explicit linking. The GetProcAddress() function fails! I understand that it is because when Dll is built , the names of exported functions are changed. If I use extern "C" while exporting then I can't overload the functions.

code of the dll written in a .cpp file is:

#define DLLEXPORT __declspec(dllexport)

DLLEXPORT int MySquareFunction(int);
DLLEXPORT double MySquareFunction(double);

int MySquareFunction(int i)
{
return i*i;
}

double MySquareFunction(double i)
{
return i*i;
}


code of the client is:

#include <iostream.h>
#include <windows.h>

int main(void)
{
int i ,ii;
double d,dd;
typedef int (*FPTR1)(int);
typedef double (*FPTR2)(double);
HINSTANCE hInstance;
FPTR1 fp1;
FPTR2 fp2;


hInstance = LoadLibrary("F:\\nishant\\My Code\\StudyofDlls\\cpp\\ExpLink\\ExpCppDllProj\\De bug\\ExpCppDllProj.dll");
if(hInstance != NULL)
{
fp1 = (FPTR1) GetProcAddress(hInstance,"MySquareFunction");
if(fp1 != NULL )
{
cout<<"\nEnter an integer: ";
cin>>i;
ii = (*fp1)(i);
cout<<"\nSquare of "<<i<<" is: "<<ii;
}
else
{
cout<<"\nThe address of int MySquareFunction(int) function could not be located.";
}

fp2 = (FPTR2) GetProcAddress(hInstance,"MySquareFunction");
if(fp2 != NULL )
{
cout<<"\nEnter a double: ";
cin>>d;
dd = (*fp2)(d);
cout<<"\nSquare of "<<d<<" is: "<<dd;
}
else
{
cout<<"\nThe address of double MySquareFunction(double) function could not be located.\n";
}

FreeLibrary(hInstance);
}
else
{
cout<<"\nThe LoadLibrary() function failed.\n";
}
return 0;
}

Hi Fordy,
Thanx for clarification, but that means i can't export classes and then import them explicitlv with GetProcAdress().

Regards

Yes you can export objects, but it's not straight forward.

Normally, you export a function to create an instance of your object and return a pointer to it. You also need to export a function to destroy it.

In addition, if you want compatability between compilers, and/or between different versions of your DLL, you need to use pure virtual base classes and export pointers to these.

Here's some info:

www.bcbdev.com/articles/vcdll2.htm