VC++ .NET 2002: Dynamically Load DLL program got Error C2664

[Scott Chang]

Hi all
I copied the following VC++ 6.0 code (written by someone in the website) to my VC++ .Net 2002-Windows XP Pro PC
////****Solution 'dyndllclass' (2 projects)***///
///***dynapp****(1 st project)***//
//----dynapp.cpp----/
#include <windows.h

#include "dynclass.h

int main ( void
PFNCREATEMYCLAS S pfnCreateMyClas s = NULL
PFNDELETEMYCLAS S pfnDeleteMyClas s = NULL
PFNGETCLASSMETH OD pfnGetClassMeth od = NULL
PMYCLASSMETHOD pDoSomethingUse ful = NULL
CMyClass* pMyClass = NULL

HANDLE hDll = INVALID_HANDLE_ VALUE

hDll = LoadLibrary ( "dynclass.d ll")

if ( INVALID_HANDLE_ VALUE == hDll
return ( -1)

pfnCreateMyClas s = ( PFNCREATEMYCLAS S) GetProcAddress ( hDll,
"CreateMyCl ass
)

pfnDeleteMyClas s = ( PFNDELETEMYCLAS S) GetProcAddress ( hDll,
"DeleteMyCl ass
)

pfnGetClassMeth od = ( PFNGETCLASSMETH OD) GetProcAddress ( hDll,
"GetClassMe thod
)

if ( pfnDeleteMyClas s
&& pfnCreateMyClas
&& pfnGetClassMeth o
// et voila - an instance of CMyClass
pMyClass = ( pfnCreateMyClas s) ()

pDoSomethingUse ful = ( pfnGetClassMeth od ())

( pMyClass->*pDoSomethingU seful)()

( pfnDeleteMyClas s ( pMyClass))
FreeLibrary ( hDll)

return ( 0)

//----dynclass.h----/
#ifndef __DYNCLASS_
#define __DYNCLASS_

#include <windows.h

#ifdef _DLL // assume this is defined when we build the dl
#define _DYNLINK __declspec( dllexport
#els
#define _DYNLINK __declspec( dllimport
#endi

class _DYNLINK CMyClas
{
public
CMyClass ()

virtual ~CMyClass()

void DoSomethingUsef ul()
}

typedef void ( CMyClass::*PMYC LASSMETHOD)()

#ifndef _DL
typedef CMyClass* ( *PFNCREATEMYCLA SS)()
#els
_DYNLINK CMyClass* CreateMyClass()
{
return ( new CMyClass())

#endi

#ifndef _DL
typedef void ( *PFNDELETEMYCLA SS)( CMyClass*)
#els
_DYNLINK void DeleteMyClass ( CMyClass* pObj)
{
delete pObj

#endi

#ifndef _DL
typedef PMYCLASSMETHOD ( *PFNGETCLASSMET HOD)()
#els
_DYNLINK PMYCLASSMETHOD GetClassMethod ()
{
return &CMyClass::DoSo methingUseful

#endi
#endif // ndef __DYNCLASS_
///****dynclass*** *(2nd project)**//
//----dynclass.cpp---/
#include <windows.h
#include "dynclass.h

HINSTANCE g_hinstThisDll

static BOOL g_bCrippledOS = FALSE
static OSVERSIONINFO g_osviVerInfo

extern "C" int APIENTRY DllMain ( HINSTANCE hInstance,
DWORD dwReason,
LPVOID lpReserve
BOOL bRC = TRUE

if ( DLL_PROCESS_ATT ACH == dwReason

// Extension DLL one-time initializatio
g_hinstThisDll = hInstance

g_osviVerInfo.d wOSVersionInfoS ize = sizeof ( OSVERSIONINFO)

GetVersionEx( &g_osviVerIn fo)

if ( VER_PLATFORM_WI N32_WINDOWS == g_osviVerInfo.d wPlatformId
g_bCrippledOS = TRUE

return ( TRUE)
CMyClass::CMyCl ass (

OutputDebugStri ng ( "This is CMyClass::CMyCl ass()\n")
CMyClass::~CMyC lass(

OutputDebugStri ng ( "This is CMyClass::~CMyC lass()\n")
void CMyClass::DoSom ethingUseful()

OutputDebugStri ng ( "This is CMyClass::DoSom ethingUseful()\ n")

//---dynclass.def---/
LIBRARY dynclass.dl
EXPORT
CreateMyClass @2 PRIVATE ; object creatio
DeleteMyClass @3 PRIVATE ; object destructio
GetClassMethod @4 PRIVATE ; method acces

//----dynclass.h---/
#ifndef __DYNCLASS_
#define __DYNCLASS_

#include <windows.h

#ifdef _DLL // assume this is defined when we build the dl
#define _DYNLINK __declspec( dllexport
#els
#define _DYNLINK __declspec( dllimport
#endi

class _DYNLINK CMyClas
{
public
CMyClass ()

virtual ~CMyClass()

void DoSomethingUsef ul()
}

typedef void ( CMyClass::*PMYC LASSMETHOD)()

#ifndef _DL
typedef CMyClass* ( *PFNCREATEMYCLA SS)()
#els
_DYNLINK CMyClass* CreateMyClass()
{
return ( new CMyClass())

#endi

#ifndef _DL
typedef void ( *PFNDELETEMYCLA SS)( CMyClass*)
#els
_DYNLINK void DeleteMyClass ( CMyClass* pObj)
{
delete pObj

#endi

#ifndef _DLL
typedef PMYCLASSMETHOD ( *PFNGETCLASSMET HOD)();
#else
_DYNLINK PMYCLASSMETHOD GetClassMethod ()
{
return &CMyClass::DoSo methingUseful;
}
#endif

#endif // ndef __DYNCLASS_H
/////////////////////////////////////////////////////
When I did 'Build' on this Solution, I got the following:
c:\Kraus-DynDLL\Kraus\dy napp.cpp(23): error C2664: 'GetProcAddress ' : cannot convert parameter 1 from 'HANDLE' to 'HMODULE'
c:\Kraus-DynDLL\Kraus\dy napp.cpp(27): error C2664: 'GetProcAddress ' : cannot convert parameter 1 from 'HANDLE' to 'HMODULE'
c:\Kraus-DynDLL\Kraus\dy napp.cpp(31): error C2664: 'GetProcAddress ' : cannot convert parameter 1 from 'HANDLE' to 'HMODULE'
c:\Kraus-DynDLL\Kraus\dy napp.cpp(48): error C2664: 'FreeLibrary' : cannot convert parameter 1 from 'HANDLE' to 'HMODULE'
////////////////////////////////////////////////////////////////
I looked it up in MSDN and I found that Compiler Error C2664: 'function': cannot convert parameter number from
'type1' to 'type2'. I do not know how to correct this problem. Please help and tell me how to solve this problem
in my VC++ .NET 2002 (VC++ 7.0).
Thanks in advance,
Scott Chang

[Jeff Partch [MVP]]

"Scott Chang" <an*******@disc ussions.microso ft.com> wrote in message
news:16******** *************** ***********@mic rosoft.com...

HANDLE hDll = INVALID_HANDLE_ VALUE;

hDll = LoadLibrary ( "dynclass.dll") ;

if ( INVALID_HANDLE_ VALUE == hDll)
return ( -1);

pfnCreateMyClas s = ( PFNCREATEMYCLAS S) GetProcAddress ( hDll,
"CreateMyCl ass"
When I did 'Build' on this Solution, I got the following:
c:\Kraus-DynDLL\Kraus\dy napp.cpp(23): error C2664: 'GetProcAddress ' :

cannot convert parameter 1 from 'HANDLE' to 'HMODULE'

Hmm...Try it like this...

HMODULE hDll = (HMODULE)INVALI D_HANDLE_VALUE;

--
Jeff Partch [VC++ MVP]

[Tomas Restrepo \(MVP\)]

Hi Scott, Jeff,

HANDLE hDll = INVALID_HANDLE_ VALUE;

hDll = LoadLibrary ( "dynclass.dll") ;

if ( INVALID_HANDLE_ VALUE == hDll)
return ( -1);

pfnCreateMyClas s = ( PFNCREATEMYCLAS S) GetProcAddress ( hDll,
"CreateMyCl ass"
When I did 'Build' on this Solution, I got the following:
c:\Kraus-DynDLL\Kraus\dy napp.cpp(23): error C2664: 'GetProcAddress ' :

cannot convert parameter 1 from 'HANDLE' to 'HMODULE'

Hmm...Try it like this...

HMODULE hDll = (HMODULE)INVALI D_HANDLE_VALUE;

Since LoadLibrary() returns NULL on failure, and not INVALID_HANDLE_ VALUE, a
wiser choice would be to do this, instead:
HMODULE hDll =NULL;
hDll = LoadLibrary ( "dynclass.dll") ;

if ( NULL == hDll)
return ( -1);

--
Tomas Restrepo
to****@mvps.org

[Jeff Partch [MVP]]

"Tomas Restrepo (MVP)" <to****@mvps.or g> wrote in message
news:%2******** ********@TK2MSF TNGP10.phx.gbl. ..

Since LoadLibrary() returns NULL on failure, and not INVALID_HANDLE_ VALUE, a wiser choice would be to do this, instead:
HMODULE hDll =NULL;
hDll = LoadLibrary ( "dynclass.dll") ;

if ( NULL == hDll)
return ( -1);

Yep! :) Thanks, Tomas.

--
Jeff...

[Scott Chang]

Hi Jeff and Thomas
The statment of HMODULE hDLL = NULL; works. Thank you both
Scott Chan