Access LIB functions through DLL

[JimmyFo]

Hi, I am trying to expose the functions in a .lib file I have through a .dll file. This is because the program I am working with (Progress 4GL) can not utilize .lib files - it can only call .dll files.

My question is, how can I create a DLL that exposes the .lib functions? I would like to create a DLL project, load the .lib (?) and then call the .lib functions from within an exposed DLL function. Can I do this?

Thanks,
James

 

[cpjust]

You need to export the functions:

http://msdn.microsoft.com/library/d...om_a_dll_using___declspec.28.dllexport.29.asp

 

[JimmyFo]

Thanks, I've done some work on it. I used HMODULE and LoadLibrary to open the .lib file inside one of the exported functions and I now have an error.

The lib has a namespace defined in it (called "oralib") and to use the .lib's functions, I need to do something like:

oralib::connection cn;

When I do this after the LoadLibrary, it says "namespace 'oralib' not defined'". Do you know why this is?

Thanks,
James

 

[JimmyFo]

Hi, let me clarify some of the code I'm using:

DLLCode.h

#pragma once

#ifdef DLLDIR_EX
   #define DLLDIR  __declspec(dllexport)   // export DLL information
#else
   #define DLLDIR  __declspec(dllimport)   // import DLL information
#endif 

// The extern "C" declaration allows mixed languages compactability,
// it prevents the C++ compiler from using decorated (modified)
// names for the functions 
extern "C" { 
       void DLLDIR InsertToOracle();
}; 

class DLLDIR DLLclass
{
   public:
      DLLclass();				// Class Constructor
      ~DLLclass();				// Class destructor
      int CreateInsert();	// Class function Add
};

DLLCode.cpp

#include "Stdafx.h"
#include "DLLCode.h"
#include <iostream> 

using namespace std; 

void InsertToOracle()
{
	HMODULE hMod;				//Handle to library module
	BOOL bRes;					//Check if unloaded successfully
	hMod = LoadLibrary("oralib.lib");

	oralib::connection cn;

	cn.open ("server_name", "scott", "tiger");
	cn.execute ("create table temp_table ( n numeric )");
	cn.execute ("insert into temp_table values (1)");
	oralib::resultset &rs = *cn.select ("select * from temp_table");
	// ...
	rs.release ();
	cn.execute ("drop table temp_table");

	bRes = FreeLibrary(hMod);
}; 


DLLclass::DLLclass()
{
}; 
DLLclass::~DLLclass() {}; 

int DLLclass::CreateInsert()
{
	int b = 1;
	return b;
};

Question: what is the difference of DLLImport and LoadLibrary?