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System DSN are stored in the registry at HKEY_CURRENT_USER/SOFTWARE/ODBC/OBBC.INI
youc can read the DSN named key.
Ritu Kwatra
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Hi
I have a TabCtrl. The user should finish the operation on Tab 1 (press a button in the tab 1) before being able to access Tab 2 and the others.
How can i make this restriction?
/\|-||\/|/\|)
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hi
On button of Tab1 declare the extern global value set to specific value and on tab2 check that value if u get that allow it or else set the focus to tab1
cheers
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I write a program,use the global msg hook.Although the wm_keydown 、wm_mousemove and other msg can hook,but the wm_destroyclipboard、WM_DRAWCLIPBOARD and other clip msg cann't hook.
Can anyone tell me why?How can i to do ? Thanks a lot!
hook = SetWindowsHookEx(
WH_GETMESSAGE,
(HOOKPROC)msghook,
hInstance,
0);
---------------------
if(code < 0)
{ /* pass it on */
CallNextHookEx(hook, code,
wParam, lParam);
return 0;
} /* pass it on */
LPMSG lpEvent = (LPMSG)lParam;
if( lpEvent->message == WM_DESTROYCLIPBOARD)
{
MessageBox(NULL,"click!","click",MB_OK);
nn=FALSE;
}
// Pass the message on to the next hook
return CallNextHookEx(hook, code,
wParam, lParam);
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There is modal dialog and on its DoModal() we start a thread
CPBarDlg dlg;
dlg.DoModal();
BOOL CPBarDlg::OnInitDialog()
{
CDialog::OnInitDialog();
// TODO: Add extra initialization here
m_event = CreateEvent(0,true,false,0);
p->event = m_event;
p->quit = 0;
pTH = AfxBeginThread((AFX_THREADPROC)&annthread,p,0,0,0,0);
return TRUE; // return TRUE unless you set the focus to a control
// EXCEPTION: OCX Property Pages should return FALSE
}
void CPBarDlg::OnClose()
{
// TODO: Add your message handler code here and/or call default
p->quit = 1;
WaitForSingleObject(m_event, INFINITE); //returns when m_event in signaled state
//hang here sometimes in Release mode??????
CloseHandle(m_event);
CDialog::OnClose();
}
/////////////////////////////////////////////////////////////////////////////
//////////////////////////////THREAD/////////////////////////////////////////
UINT annthread(LPARAMS p)
{
while(!p->quit)
{
//do some calculations.... req about 10-20ms
}
SetEvent(p->event);
return 0;
}
///////////////////////////////////////////////////////////////////////////////
So in order to end thread before we close CPBarDlg we set p->quit = 1 and wait untill event signaled by thread. But it is not set in thread in Release mode and OnClose() handler start to wait forever for WaitForSingleObject(m_event, INFINITE)??? whats wrong
9ine
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Did you declare the quit variable with the volatile modifier?
Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro
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why? no I didnt. it is just a structure
typedef struct _params
{
int quit;
HANDLE event;
...
...
etc...
}PARAMS p, LPARAMS *p;
and then just:
PARAMS p; //in dialog header file
and
p.quit = 0;
p.event = ...
... etc
beforecreating a thread and passing PARAMS to it.
9ine
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You need to declare quit as volatile, which guarantees that the compiler won't do any optimization, which is what is happening in your case. The compiler probably decided that quit was not being modified in the while loop and decided to ignore the check altogether.
Declaring it as volatile prevents the compiler from doing that optimization, my guess is that would solve your problem.
Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro
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yes I choosed optimization in Release mode, interesting that it prevents checking variable if it is not modified in while loop ) . I noted that it is terminated about 1 to 4 not terminated cases. Will check it with volatile mod.
9ine
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Intresting! volatile modifier does not help?
I noticed that thread accesses quit variable only after terminating of OnClose() method where quit variable modified, so what is the purpose of Events after this incident?
9ine
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hi
Please help me.
I have implemented class in DLL(in vc++). now i want to access
that class in vb. how can i do this.
Is it possible to create instance of class in vb.
if anybody knows please tell me about this.
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rajesh_kapure wrote:
I have implemented class in DLL(in vc++)
You mean a COM Dll. Right?
You can add a reference to your COM Dll in VB through Project->References. After that you can use the COM Dll's methods.
Steve Mayfield: "Coding in VB is like riding a tricycle...once you figured out how to peddle, its really hard to fall off."
My Articles
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Thanks Aamir
i already done that thing.
but whenever i add a refference of COM Dll it gives message "can't add
reference to the specified file"
can you give me step or source code for how to create COM DLL in vc++.
so that i will better understand.
Rajesh
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No, Can you tell me step by step how to create COM DLL.
or send me source code for that.
Rajesh
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Hello.
I can't solve one problem.
I need on WM_KEYDOWN set focus on Edit and to add to Edit symbol,that was pressed.Also I need to save information about CapsLock and Shift.
Can anyone help me?
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Hi,
Is there any alogrithm for conversion between UTF8 and UTF16. Need help reg this. Urgent.
Thanks
Cool Ju 
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Hi
I have the problem while calling webservice created in ASP.net through vc++.
Any kind of help is appreciated.
cheers
hi
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I am trying to write a DLL that will allow my visual basic application to receive Window messages. Problem is, when my DLL trys to register the hook, it crashes. Here is the code to my DLL:
////////// Header Files //////////
#include <windows.h>
#include <string.h>
#include "dllutil.h"
#include <winuser.h>
#pragma data_seg ("GlobalData")
long CallBackFunctionPtr =0;
HANDLE DLLHandle =0;
HHOOK HandleToHook =0;
long VBFunctionPtrAddress =0;
#pragma data_seg()
#pragma comment(linker, "/section:GlobalData,RWS")
//end of Global Memory setup
//This is my Generic Hook Function
LRESULT CALLBACK WindowsMessageMonitorHook(int nCode, WPARAM wParam,LPARAM lParam)
{
tagCWPSTRUCT *CPWStructPtr;
//Initlize the pointer not sure if this is correct.
CPWStructPtr = (tagCWPSTRUCT *)lParam;
//this is how call vb back
typedef void (__stdcall *FNPTR)(long x);
FNPTR FunctionCall;
if (nCode == HC_ACTION)
{
//Send Message Back to VB routine
FunctionCall = (FNPTR)VBFunctionPtrAddress;
FunctionCall((long) CPWStructPtr->message);
}
return CallNextHookEx(HandleToHook,nCode,wParam,lParam);
}
HHOOK StartCallBack()
{
//debug message - I can see this message displayed OK
::MessageBox(NULL,"Set Windows Hook","C++ DLL",0);
//but when I single step on this next line, it crashes
HandleToHook = SetWindowsHookEx(WH_CALLWNDPROCRET,
WindowsMessageMonitorHook,
(HINSTANCE)DLLHandle, 0);
//I never see this message.
//Even if I type case WindowsMessageMonitorHook as
//HOOKPROC I get the same resutls.
//I never see this message.
::MessageBox(NULL,"Hooks Have been set","C++ DLL",0);
return HandleToHook;
}
// Receives the address of a Visual Basic function and calls
// it.
extern "C" HHOOK __declspec(dllexport) __stdcall CALLBACK
CallBackExample(long Addr1)
{
HHOOK HookResults;
//Store in global variable
VBFunctionPtrAddress = Addr1;
//Startup MessageMonitorHook
HookResults = StartCallBack();
if (HookResults == 0)
{
::MessageBox(NULL,"Start Hook Results =
0","C++ DLL",0);
}
else
{
::MessageBox(NULL,"Start Hook Results not
zero.","C++ DLL",0);
}
return HookResults;
}
extern "C" BOOL __declspec(dllexport) __stdcall CALLBACK
StopWindowMonitorHook()
{
BOOL Results;
Results = UnhookWindowsHookEx(HandleToHook);
return Results;
}
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
//save dll handle in global memory
DLLHandle = hModule;
switch(ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
break;
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
Any Idea why it crashes?
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A little tip first: Call CallNextHookEx(HandleToHook,nCode,wParam,lParam); at the beginning of the hook function, else it could cause kinda deadlock for every application running.
Don't try it, just do it! 
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I tried it, no help. It never makes it to the HOOK call back function. So it dies on the SetWindowsHookEx function.
It dies right here:
HandleToHook = SetWindowsHookEx(WH_CALLWNDPROCRET,
WindowsMessageMonitorHook,(HINSTANCE)DLLHandle, 0);
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Is anybody knows how to rebuild MFC files under the folder "Microsoft Visual Studio\VC98\MFC\SRC", I know roughly there are two processes involved, one is to add the "Microsoft Visual Studio\VC98\Lib" to the "path" Environment variable, the other is to nmake certain makefile!But haven't seceed yet!
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