C / C++ / MFC

toxcct11-Oct-06 6:32

toxcct

11-Oct-06 6:32

why on earth do you want to do such a thing ?

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

Rick York11-Oct-06 6:43

Rick York

11-Oct-06 6:43

Just guessing but maybe this : http://www.codeproject.com/script/comments/forums.asp?forumid=1647&select=1707354&df=100#xx1707354xx[^]

toxcct11-Oct-06 6:47

toxcct

11-Oct-06 6:47

i still don't understand why he would want to close stdandard stream for this...

TOXCCT >>> GEII power

[VisualCalc 3.0 updated ][Flags Beginner's Guide new! ]

viliam11-Oct-06 6:49

viliam

11-Oct-06 6:49

you right,
lame and oggenc are during stream encoding using stdin
and i dont know how to let them know that no more data is comming.

viliam

David Crow11-Oct-06 7:11

David Crow

11-Oct-06 7:11

What are those programs expecting as a "termination" character?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Re: uml for n-queens problem

viliam11-Oct-06 7:24

viliam

11-Oct-06 7:24

i dont know, this programs doesn't say
it is maybe simple and obvious but i have no idea how to use it for stream
processing.
...and data are raw PCM data (wav audio) and there is probably no
chance to say "this character" means end.

viliam

uml for n-queens problem

pimpernel11-Oct-06 6:31

pimpernel

11-Oct-06 6:31

am stuck with the uml diagrams for the n-queens problem and need assistance. need to identify entities and their relations

Galatei12-Oct-06 0:26

How does code find correct VTBL?

12-Oct-06 0:26

http://www.durangobill.com/N_Queens.html

sawerr11-Oct-06 6:25

sawerr

11-Oct-06 6:25

i really don't understand how code finds correct VTable(not function)

I read here : http://www.parashift.com/c++-faq-lite/virtual-functions.html#faq-20.4
ıt says:"The idea is to change each Der object's v-pointer so it points at its class's v-table. (This is not a second v-pointer; it's the same v-pointer that was defined in the base class, Base; remember, the compiler does not repeat step #2 in class Der"

I confused here.
How many are vtables created?
amount of base+derived class.One VTABLE for each.But all of them has one VPTR.IS this right?

So if there is a VTABLE for each class but one VPTR; How can code find the correct function?
I know calling virtual func. means calling an offset.But this offset is in the class's VTABLE.But first it must find one more offset that indicate correct class?
Am i wrong?

For example i have one base class and one virtual funct. and three derived class in a dll.Here when i call to 3. derived class virtual function from base class pointer from my exe.Here first it must find 3. VTABLE and and first offset.Right?
But here we have only one VPTR so haw can it find 3. VTABLE and then offset of the function?

I am looking for your answers
Thanks.

Re: How does code find correct VTBL?

prasad_som12-Oct-06 20:56

prasad_som

12-Oct-06 20:56

sawerr wrote:
How many are vtables created?

one vtbale for each class having virtual function.

sawerr wrote:
But all of them has one VPTR.IS this right?

yes, but if derived class class is having virtual function, it uses vptr declared in base class, only thing its initialized to dervied class vtable.

sawerr wrote:
So if there is a VTABLE for each class but one VPTR; How can code find the correct function?
I know calling virtual func. means calling an offset.But this offset is in the class's VTABLE.But first it must find one more offset that indicate correct class?
Am i wrong?

vptr discussed above is initialized with each class's vtable in constructor of each class. So, lets say you are creating object of dervied class, then base class's constructor will call first, initializing vptr to base class's vtable. But then derived class's constructor class will be called, reinitializing it to derived class's vtable. And function would be found by indexing. because, that function will have addresses of that class's functions.

sawerr wrote:
For example i have one base class and one virtual funct. and three derived class in a dll.Here when i call to 3. derived class virtual function from base class pointer from my exe.Here first it must find 3. VTABLE and and first offset.Right?
But here we have only one VPTR so haw can it find 3. VTABLE and then offset of the function?

Not clear about question . Confused | :confused:

Prasad
Notifier using ATL | Operator new[],delete[][^]

PropertySheet as the main application window?

petrkar11-Oct-06 5:54

petrkar

11-Oct-06 5:54

I tried to make the CPropertySheet derived class instance the main applacation window in the very start of MFC standard machinery - somehow like follows:

<small>...<br />
CMyPropertySheet PropSheet("Test Property Sheet",NULL);<br />
m_pMainWnd = &PropSheet;<br />
...</small>

but I did not succeed (even if the PropSheet is initialized correctly).
Of course, I can have silent, invisible window or dialog "behind" PropertySheet, but it seems to me rather idle.
Thanks for any advice and/or experiences...

Re: PropertySheet as the main application window?

Mark Salsbery11-Oct-06 6:37

Mark Salsbery

11-Oct-06 6:37

Are you really doing it this way?

...
CMyPropertySheet PropSheet("Test Property Sheet",NULL);
m_pMainWnd = &PropSheet;
...

PropSheet needs to be a member of your app class.
It also needs to be created.

Mark

Re: PropertySheet as the main application window?

David Crow11-Oct-06 7:13

David Crow

11-Oct-06 7:13

It's not necessary to mess with the app class. Use AppWizard to create a dialog-based application. Then edit the dialog's .h and .cpp files, changing CDialog to CPropertySheet. Add the pages in the sheet's constructor.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Problem with modeless dialog - PLEASE HELP!

arrayjet_c++11-Oct-06 5:03

arrayjet_c++

11-Oct-06 5:03

Hi there,

I've been stuck on this problem for over a day now and it's driving me crazy:

From the mainframe i create a new dialog (modeless):

void CMainFrame::OnMachineInit()
{
CInitmachinedialog *initmachinedialog;
initmachinedialog = new CInitmachinedialog;
initmachinedialog -> Create (IDD_MACHINEINITDIALOG, this);
initmachinedialog -> ShowWindow(SW_SHOW);
initmachinedialog -> init_pre_operations(2);
}

void CInitmachinedialog::init_pre_operations(int init_status)
{
[...]
running = TRUE;
THREADSTRUCT *_param = new THREADSTRUCT;
param->_this = this;
AfxBeginThread (init_thread,_param,THREAD_PRIORITY_ABOVE_NORMAL,0,0,NULL);
}

UINT CInitmachinedialog::init_thread (LPVOID param) // thread 1
{
THREADSTRUCT* ts = (THREADSTRUCT*)param;
while (running) ts->_this->initmachine(); // while (running = true) the thread is running
ts->_this->DestroyWindow();
return 0; // same as afxendthread(0)
}

The "destroywindow" command has no effect? It doesn't close the dialog or do anything?

Any idea why???? Smile | :)

led mike11-Oct-06 6:01

led mike

11-Oct-06 6:01

arrayjet_c++ wrote:
Any idea why?

Proably because MFC uses thread local storage so the _this pointer is not available in the worker thread. There are really old KB Articles about this problem. You might look into using PostThreadMessage() to send a message to the dialog and then it would handle the message and call DestroyWindow() in the proper thread.

led mike

Galatei12-Oct-06 0:03

12-Oct-06 0:03

Hi,

Have you actually checked if DestroyWindow function has ever been reached?
Is running variable a member of CInitmachinedialog class, and if so, is it static?
Are you sure that ts->_this->DestroyWindow(); is working at all? eg. isn't overriden.

Try putting ts->_this->DestroyWindow(); inside init_pre_operations function to test it outside of a thread.

Regards

arrayjet_c++12-Oct-06 5:48

arrayjet_c++

12-Oct-06 5:48

Yes the destroywindow function is definitely being reached.

Running is declared as static volatile and is used to monitor the working thread,

this is how THREADSTRUCT is definied in my header file:

typedef struct THREADSTRUCT
{
CInitmachinedialog* _this;
}THREADSTRUCT;

Any ideas?

Galatei12-Oct-06 6:58

12-Oct-06 6:58

Hi again,

Try to replace ts->_this->DestroyWindow(); with

ts->_this->SendMessage(WM_CLOSE);

It definitely works.

Regards

arrayjet_c++12-Oct-06 22:57

arrayjet_c++

12-Oct-06 22:57

No i'm afraid it doesn't Frown | :(

ts->_this->SendMessage(WM_CLOSE) has no effect - same as ts->_this->DestroyWindow() really.

Galatei12-Oct-06 23:00