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How do I link a DLL to a Win32 EXE for use??

Sat, 28 Oct 2000 16:55:45 -0700

I'm trying to get my executeable file to load a few DLLs I have made and compiled so that I don't have to put a ton of functions into the actual executeable, but I have NO experience with DLLs. Can somebody help me figure out how to use both load-time linking (Borland says I have to link with the .LIB for this one?) and run-time linking (for stuff such as the main menu popping up when you press ESC). I would REALLY appreciate any help that anybody can give me. Thanks for your time. 
 
-Seph

Re: How do I link a DLL to a Win32 EXE for use??

Mon, 30 Oct 2000 09:53:56 -0700

Hello Speh.. 
 
For linking in compile time, you only need to add the lib file to your project, then #include the header file and off you go. For example, you have a void myfunc( int x ) in the DLL, your include file will look like this: 
// mydll.h 
#if !defined( INC_MYDLL ) 
#define INC_MYDLL 
 
#if defined( __cplusplus ) 
extern "C" { 
#endif // __cplusplus 
 
// list the functions here 
void WINAPI myfunc( int x ); 
 
#if defined( __cplusplus ) 
} 
#endif // __cplusplus 
 
#endif // INC_MYDLL 
 
If you have a problem with any of the above, post again! 
 
If you want to use a DLL created by someone else, then dont forget to IMPLIB it beforehand. BCB and VC++ both use different format for thier import libraries. 
 
To use the DLL above in run-time, you would do it like this: 
 
typedef void (*WINAPI pMYFUNC)( int ); 
 
HINSTANCE hInst = LoadLibrary( "mydll.dll" ); 
pMYFUNC pMyFunc = (pMYFUNC) GetProcAddress( hInst, "myfunc" ); 
 
// and run it.. 
pMyFunc(10); 
 
// You might want to do this before you are done 
FreeLibrary( hInst ); 
 
I didnt understand what you mean by main menu and ESC... 
 
Hope this helped a bit

Re: Re: How do I link a DLL to a Win32 EXE for use??

Mon, 30 Oct 2000 17:07:09 -0700

OK, I didn't make a header file for the dll before. All I did was make a file with the functions in it, and then compiled to a dll, with no errors or warnings. So what would this header file be used for? Just linking purposes?? 
 
-Seph

Re: Re: Re: How do I link a DLL to a Win32 EXE for use??

Tue, 31 Oct 2000 14:47:46 -0700

That header file is the interface to your DLL. Remember, a DLL is a library, and a library is all about packaging some piece of code from the user with only an interface exposed. 
 
For example, GDI.EXE (its a DLL renamed EXE really) is the DLL, windows.h is the interface that has the prototypes of the functions inside that DLL, like int WINAPI SetPixel( HDC hDC, int x, int y ); 
 
: OK, I didn't make a header file for the dll before. All I did was make a file with the functions in it, and then compiled to a dll, with no errors or warnings. So what would this header file be used for? Just linking purposes?? 
: 
: -Seph 
: 
: 
:

Re: Re: Re: Re: How do I link a DLL to a Win32 EXE for use??

Tue, 31 Oct 2000 15:55:27 -0700

So it would be like this? 
 
//the dll itself 
int hitval(int level, int str, int agi, int opagi) 
{ 
stuff here; 
return hit; 
} 
 
 
//the header 
*stuff you showed me here* 
int hitval(int level, int str, int agi, int opagi); 
 
 
I'm going to try it real fast and see what happens. This "fight.dll" is very important to the program though, considering it has all battle info in it. 
 
-Seph

Re: Re: Re: Re: How do I link a DLL to a Win32 EXE for use??

Tue, 31 Oct 2000 16:08:58 -0700

OK, just got done trying it. I pasted what you posted into the header file, and changed it from INC_MYDLL to INC_FIGHT (fight.dll/fight.cpp) and the void function I replaced with "int hitval(int level, int str, int agi, int opagi);". I am still getting "unresolved external referenced from AoY.OBJ". I have added the .lib file to the project, to be linked with the executeable. Any ideas?? 
 
-Seph

Re: Re: Re: Re: Re: How do I link a DLL to a Win32 EXE for use??

Wed, 01 Nov 2000 07:51:22 -0700

You still need to tell the compiler which functions to export from the DLL. This can be done in 2 ways, the __dllimport/__dllexport or through a DEF file, I use DEF files always because it lets me define the ordinal numbers of those functions myself, meaning, if I update the DLL by adding new functions, the EXE's need not to be recompiled. A good practice! 
 
OK, lets write this down.. I think you know how to create a Win32 DLL project, so here are the files to add. 
 
First of all here's the H file: 
//---------------------------------------------------------------------------- 
// fight.h 
#if !defined( INC_FIGHT ) 
#define INC_FIGHT 
 
#if defined( __cplusplus ) 
extern "C" { 
#endif // __cplusplus 
 
int WINAPI hitval(int level, int str, int agi, int opagi); 
 
#if defined( __cplusplus ) 
} 
#endif // __cplusplus 
 
#endif // INC_FIGHT 
//---------------------------------------------------------------------------- 
 
And the CPP file 
//---------------------------------------------------------------------------- 
// fight.cpp 
#include <windows.h> 
#include "fight.h" 
 
extern "C" 
int WINAPI hitval(int level, int str, int agi, int opagi) 
{ 
// for a test, show values in a message box 
char buffer[ 80 ]; 
wsprintf( buffer, 
"level = %d\nstr = %d\nagi = %d\nopagi = %d", 
level, str, agi, opagi ); 
MessageBox( NULL, buffer, "in dll", MB_OK ); 
 
return 10; 
} 
//---------------------------------------------------------------------------- 
 
And the DEF file 
;---------------------------------------------------------------------------- 
; fight.def 
LIBRARY FIGHT.DLL ; should be the same name as the result DLL! 
DESCRIPTION 'This is the fight DLL!' 
HEAPSIZE 10000 
EXPORTS 
hitval @100 ; you can add more functions here: function name @101 and so on 
;---------------------------------------------------------------------------- 
 
Note that comments in DEF file are ; comment... much like ASM comments. 
 
That's it, compile/link the lot, you have a DLL and a LIB file. Now create a simple test EXE something like this 
// ---------------------------------------------------------------------------- 
// test.cpp 
#include <windows.h> 
#include "fight.h" // make sure this points to the correct path 
 
int WINAPI WinMain( HINSTANCE, HINSTANCE, LPSTR, int ) 
{ 
int ret = hitval( 1, 2, 3, 4 ); 
char buffer[ 80 ]; 
wsprintf( buffer, "returned %d", ret ); 
MessageBox( NULL, buffer, "in exe", MB_OK ); 
return 0; 
} 
//---------------------------------------------------------------------------- 
 
Add fight.lib to this project, make sure fight.dll is somewhere along the path, run.. It should work fine. 
 
Hope this helps 
 
: OK, just got done trying it. I pasted what you posted into the header file, and changed it from INC_MYDLL to INC_FIGHT (fight.dll/fight.cpp) and the void function I replaced with "int hitval(int level, int str, int agi, int opagi);". I am still getting "unresolved external referenced from AoY.OBJ". I have added the .lib file to the project, to be linked with the executeable. Any ideas?? 
: 
: -Seph 
:

The missing include file is windows.h (NT)

Wed, 01 Nov 2000 07:54:13 -0700

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