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I have a library file but I don't know to import it to my project.
In the Import Library field, I put "MathFuncsDll.lib" to import it but after I built the project I have an error

Linking...
Main.obj : error LNK2019: unresolved external symbol "public: static double __cdecl MathFuncs::MyMathFuncs::Add(double,double)" (?Add@MyMathFuncs@MathFuncs@@SANNN@Z) referenced in function "void __cdecl DarkGDK(void)" (?DarkGDK@@YAXXZ)
Debug\Call DLL.exe : fatal error LNK1120: 1 unresolved externals

I copy MathFuncsDll.dll, MathFuncsDll.lib, MathFuncsDll.h to the GarkGDK project.

In my program

#include "DarkGDK.h"
#include "MathFuncsDll.h"


void DarkGDK ( void )
{
dbSyncOn ( );
dbSyncRate ( 60 );

dbLoadDLL( (DWORD) "MathFuncsDll.dll" , 2 );

as I told you I have an linking error

the dll file was created by vc++ 2008, I follow the help that teach how to create dynamic link library

and I want to call the dll by DarkGDK game

what should i do??

thanks so much much much

I found the other way in vc++ help

First I should follow the help for creating a new DLL file.

Then I must Config the project.

for my GDK program

#include "DarkGDK.h""
#include "MyDll.h" //include dll header file

using namespace MathFuncs; //use the name space in the dll file

void DarkGDK ( void )
{

dbSyncOn ( );
dbSyncRate ( 60 );

dbPrint( (double) MyMathFuncs::Add( 10, 20) );
dbPrint( (double) MyMathFuncs::Subtract( 10, 20) );
dbPrint( (double) MyMathFuncs::Multiply( 10, 20) );
dbPrint( (double) MyMathFuncs:ivide( 10, 20) );

////
using this methode no need to call dbLoadDLL(...)

but I still don't know how to solve a linking error that I occured

can someone help me please ?

Show us the way you declared the function in the DLL and the header file. Both definitions must match completely.

No problem sir.

I found it in vc++ 2008 help and you can see it by the following these steps
1. In start Page of VC++2008 --> Getting started --> Learn VC++ and then VC++ help will be loaded and please wait
2. find "Creating Reusable Code (C++)" link and click it
3. fine "Creating and Using a Dynamic Link Library (C++)" link and click it
4. you will see the way that it teaches.


this is a simple dll and I will show you how to create it
//Header file
__declspec(dllexport) int Sum( int a, int b );
__declspec(dllexport) int Subtract( int a, int b );
__declspec(dllexport) int Multiply( int a, int b );
__declspec(dllexport) int Divide( int a, int b );


//Implementation file
#include "MyDLLHeader.h"

int Sum( int a, int b ) return a + b;
int Subtract( int a, int b )return a - b;
int Multiply( int a, int b )return a * b;
int Divide( int a, int b )
{
if ( b == 0 )return -1;
return a / b;
}

//Dark GDK program
#include "DarkGDK.h"
#include "MyDLLHeader.h"

void DarkGDK ( void )
{
dbSyncOn ( );
dbSyncRate ( 60 );

int result1 = Sum( 20, 20 );
dbPrint( (double) result1 );

//this is a simple way to create a dll file and use it in DarkGDK program but I still don't know how to use dbLoadDLL(...)
can someone help me please ?

thanks so much much much

You're not quite doing things right. In the main source file for the DLL you place the functions. You then put the definitions (with the __declspec(dllexport) modifier) in a header and include it.

Then you create a separate header with import definitions in (use the __declspec(dllimport) modifier), and include this in projects you want to use the DLL from.

If you want to dynamically load the DLL, use LoadLibrary and get the function addresses with GetProcAddress.

can you show me how to use dbLoadDLL and show me how to create a DLL file in the correct way.

I don't know much about DLL but I just use a DLL in a GAME

do you have an example to me?

thanks a lot