Sample - DDLs in C++: Explicit Dynamic Linking with DEF-File    Notes   Code

Simple DLL that Prints a Text:

#include "iostream.h"  //cout

BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved)
{
    return TRUE;
}

void WriteString()
{
    cout << "This string printed from DLL ..." << endl;
};

DEF-file for DLL:

LIBRARY      "DLL.DLL"

EXPORTS
    WriteString     @1 

Calling Program in Console Application:

#include <windows.h>     //for HINSTANCE
#include "iostream.h"    //for cout

void main()
{
    typedef void (* PFUNCTION)(void);
    PFUNCTION pFunction;

    HINSTANCE  hLibrary = LoadLibrary("dll.dll"); // Load the DLL now
    if (hLibrary != NULL)
    {
        /***********************************************************************
        * This code is no differerent from snippet not using DEF-file, but     *
        * importantly GetProcAddress uses original function name.              *
        ***********************************************************************/
        
        pFunction = (PFUNCTION)GetProcAddress(hLibrary, "WriteString"); 
        
        /***********************************************************************
        * Oprionally, when DEF-file is used for explicit dynamic linking, we   *
        * could use function ordinal number from DEF-file to call the function.*
        ***********************************************************************/
        
        //pFunction = (PFUNCTION)GetProcAddress(hLibrary, MAKEINTRESOURCE(1)); 

        
        if(pFunction==NULL)
        {
            cout << "Function entry point not found ..." << endl;
        }
        else
        {
            (*pFunction)();
        };
		
        FreeLibrary(hLibrary);
    }
    else
    {
        cout << "Library not found ..." << endl;
    };
}

Console Output:

This string printed from DLL ...

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