C / C++ / MFC

12-May-03 7:22

Hello,

I need to load libraries using the LoadLibrary function in my project. In the debug version of my project this works really fine, but in release mode nothing works. The app always crashes in release mode when calling a function of the DLL.

I already have read the article "How to survive the release version of your project", but it didn't help me.

Do you have any idea what it could be?

Confused | :confused:

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

valikac12-May-03 9:09

valikac

12-May-03 9:09

Compile the release version with multithreaded DLL support.

Kuphryn

Neville Franks12-May-03 13:04

12-May-03 13:04

Is this a DLL of yours or a third party. Are you linking to the release build of the DLL and if it uses MFC is it compiled to use the same build type (single/multithread/DLL/static etc.) as your app.

Neville Franks, Author of ED for Windows. www.getsoft.com
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Dominik Reichl13-May-03 0:23

13-May-03 0:23

I already solved the problem myself. It was very interesting. The Microsoft compiler unloads the DLL before I can call any function of it. It doesn't do that in the debug version. I really don't know why MSCV++ does this... I disabled the speed "optimizations" of the compiler and now it works very well!

Anyway thanks for your help
-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Neville Franks13-May-03 1:32

13-May-03 1:32

Your solution doesn't sound right to me and I think you still have a problem. I've never seen VC++ code or Windows unload a DLL for no good reason. Are you using LoadLibrary() to load the DLL or normal linking.

Neville Franks, Author of ED for Windows. www.getsoft.com
Make money with our new Affilate program

Dominik Reichl13-May-03 1:57

13-May-03 1:57

Neville Franks wrote:
Your solution doesn't sound right to me and I think you still have a problem.

At least I cannot see any problems in debug and release version any more. Also, I don't have memory leaks.
A working, dirty solution is better than a clean, not-working solution Big Grin | :-D

.

Neville Franks wrote:
I've never seen VC++ code or Windows unload a DLL for no good reason.

Me too. I've also never seen this behavior before.
Here is what exactly happenED (not any more): I load the DLL (works, I get a valid, non-NULL handle), then I get 3 functions of it (works, all function pointers are non-NULL). I have to call the first function one time, the second function about 200 times, and the last function one time. The first function worked very well. The problem now was, that when I call the second function, I can call this only once. When I attempt to make a second call to the second function, the pointer points to the last function. But I didn't change the pointer! The compiler must have done this. So instead of calling the second function again, it calls the third. After the third call, the DLL automatically unloads. What now happens is clear: the next call to the DLL function will crash the app.

I know this sounds stupid and more like a simple programming error. But I am sure there is no error by my side. I also have never seen this behaviour before. It cannot be a programming error, because now, after I disabled the optimizations, it works very fine.

This is not my first project dealing with libraries, I've build at least 5 projects which use DLLs before!

Neville Franks wrote:
Are you using LoadLibrary() to load the DLL or normal linking.

LoadLibrary, yes. The library is built with Dev-C++/GCC, the main project with MSVC++ (please don't ask why we make the DLL with Dev-C++/GCC... Big Grin | :-D

).

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Neville Franks13-May-03 2:04

13-May-03 2:04

Yes it all sounds very strange. Are you sure the function pointers weren't getting corrupted?

Neville Franks, Author of ED for Windows. www.getsoft.com
Make money with our new Affilate program

Dominik Reichl13-May-03 2:09

13-May-03 2:09

100% for sure. I assign them once to the return value of GetProcAddress and never touch them again except using them as function calls.

-Dominik

_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??

Neville Franks13-May-03 2:13

Namespace and Temmplate function

13-May-03 2:13

Dominik Reichl wrote:
100% for sure. I assign them once to the return value of GetProcAddress and never touch them again except using them as function calls.

Yes but it is always possible that some piece of erant code changed the pointer values. It would be worth checking this.

Neville Franks, Author of ED for Windows. www.getsoft.com
Make money with our new Affilate program

Shah Shehpori12-May-03 5:57

Shah Shehpori

12-May-03 5:57

Friends,
I wrote a simple template function, the purpose was to convert a "string" to "number" (just like atoi function). My function is:

namespace CP
{
	template < class T >
	T   ToNum(std::string &strNum)
	{
		T num=0;
	
		std::stringstream strm ( strNum );

		strm >> num;

		return num;

	}

}

As you can see above, the function ToNum is present inside a namespace.

In order to use this function in the main program, there are three methods to deal with namespaces. First method is:

using  namespace CP;
std::string strNum=_T("44");
std::cout << ToNum<int>(strNum)

The above method is working fine in which i initially used using namespace CP before anything else.

There is second method which is also working for me. Instead of using using namespace CP, i am directly calling the function ToNum as:

CP::ToNum<int>(strNum)

But the third method is not working for me what i am doing is:

using CP::ToNum;
ToNum<_int64>(strNum);

But strangely it is not working and compiler is giving me horrible STL errors like,

c:\test\test.cpp(32): error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'overloaded-function' (or there is no acceptable conversion)

Please tell me what is the problem ?????

Re: Namespace and Temmplate function

Brigsoft12-May-03 21:23

Brigsoft

12-May-03 21:23

Try this

#include <iostream>

int main(int argc, char* argv[])
{

_int64 a = 10;

std::cout << a << std::endl;

return 0;
}

in my system it is not working too.
Probably, the broble is in _int64,
not in yor function.

================================
Useful links

HELP! Anyone know MFC here?

Bigsteiny12-May-03 5:55

12-May-03 5:55

I need help. i must be such a retard i dont understand. I'm making an MFC SDI app, with a CButton object in the view. in OnInitialUpdate i am ::Create() ing the object fine, and ShowWindow() ing fine. The button appears... now how do i simply make an AfxMessageBox for when i click on this button!?

I've read about subclassing and it seems like it might be the way to go but i just *cant* get it to work. Any help would be appreciated...

Nitron12-May-03 6:03

Nitron

12-May-03 6:03

You need to handle the ON_BN_CLICKED message generated by the button. The easiest way to do this is to use the class wizard to automagically generate the code for you. Then in your message handler do

AfxMessageBox(_T("Your Message here."));

- Nitron

"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb

Bigsteiny12-May-03 6:09

12-May-03 6:09

Thanks, but i'm not sure that helps. The classwizard doesn't offer any mapping abilities for my object...

In the View.h i have...
CButton myButton;

then in the cpp i have

myButton.Create("Test", WS_CHILD, CRect(0,0,50,50), <br />
                      AfxGetMainWnd(), WM_USER+1);<br />
      myButton.ShowWindow(SW_SHOW);

If i go to the classwizard, under the "Message Maps" tab, i select the View as the Class Name, but then what? Theres no reference to my button anywhere. Confused | :confused:

Thanks for the help though mate, i appreciate it. any more thoughts?

-BigSteiny

David Crow12-May-03 6:54

David Crow

12-May-03 6:54

Bigsteiny wrote:
If i go to the classwizard, under the "Message Maps" tab, i select the View as the Class Name, but then what? Theres no reference to my button anywhere.

Nor should there be. ClassWizard is obviously not going to know about a control that is created at run-time.

What is your view based on?

Bigsteiny12-May-03 16:20

12-May-03 16:20

Based on? Um. It just used the AppWizard and made an SDI application.

The control is created at run time, but it's declared at compile time... not sure if this makes a difference though...

Thanks.

-Az.;)

David Crow13-May-03 2:12

David Crow

13-May-03 2:12

Bigsteiny wrote:
Based on? Um. It just used the AppWizard and made an SDI application.

Yes, but what base class was the view derived from? If you did not change any of the defaults, it's probably going to be CView. Other types are CFormView, CListView, CEditView, CHtmlView, CRichEditView, CScrollView, and CTreeView.

Besides the list control, are you going to want other controls displayed on the view?

Toni7812-May-03 7:21

Toni78

12-May-03 7:21

The best way to do this is to create a class derived from CButton.
class CMyButton : public CButton
{
// class members go here
}; // end class

And then in your MFC application you declare a member variable:
CMyButton *pButton;

Then you procceed by creating the button and showing it.
To handle messages simply go to classwizard and select CMyButton. You will be able to see the list of messages that your class can handle.

// Afterall I realized that even my comment lines have bugs

Bigsteiny12-May-03 16:18