C / C++ / MFC Discussion Boards

julvr230-Jul-07 4:59

30-Jul-07 4:59

You're trying to access a class member from within a static function. Static member functions have no concept of an instance of a class, so you can't access a member variable of an instance which doesn't exist... make sense?

So you do need to pass in the 'this' pointer, and you need to use the this pointer to access the variable.

In your case, you call Start (which does not have a class instance), which then calls Outputdata (which is also static, and thus has no class instance). Outputdata, then tries to access m_slider, but, because you have no class instance, you're essentially trying to do NULL->m_slider, which the compiler doesn't like.

So you were on the right track in the above email, but you need to take it a step further:

Try:

CMyDlg* me=(CMYDlg*)pParam
me->Outputdata(me);

Then in outputdata:

...me->m_slider...

John

Re: need help with thread functions

alberthyc30-Jul-07 6:06

alberthyc

30-Jul-07 6:06

hi, this works, but i got new problems,
in function:
Start(LPVOID pParam){
CMy61xxTestDlg* me=(CMy61xxTestDlg*)pParam;
me->param1 = 0;
do{
...
me->Outputdata(me);
me->param1++;
.....}

param1 is declared as long param1; i got error: illegal reference to non-static member 'CMyxxxDlg::param1';
then i make param1 static, it compiled,
i got error like this during linking: xxxDlg.obj error LNK2001: unresolved external symbol "public: static long CMyxxxDlg::param1

what's going on????

Re: need help with thread functions

led mike30-Jul-07 5:23

led mike

30-Jul-07 5:23

alberthyc wrote:
but it still doesn't work

Yes MFC CWnd is not freethreaded. MFC uses thread local storage to contain the map of HWND and CWnd objects, or something like that. There is like a 10 year old technical note on MSDN about it. You need to post messages to the UI thread and have it alter the User Interface.

Re: need help with thread functions

Iain Clarke, Warrior Programmer30-Jul-07 5:45

Iain Clarke, Warrior Programmer

30-Jul-07 5:45

What I do in this sort of case:

class CMyClass
{
...
   UINT MyThread ();
   static UINT __cdecl MyThread (LPVOID pParam)
   {
      CMyThead *pThis = (CMyThread *) lpParam;
      pThis->MyThread ();
   }
   ...
};


    CreateThread (blah, ...,  (LPARAM)this);

As has been said, you have to be careful about CWnds, as the the HWND -> CWnd mapping is done on a per thread basis. But if (eg) m_SliderCtrl already has been attached to a HWND, then you should be OK.

And if you're monitoring something in your thread, don't forget to Sleep (0) occasionally to be a good thread citizen on your PC!

Good luck,

Iain.

Run an exe from MFC app

koumodaki30-Jul-07 4:09

koumodaki

30-Jul-07 4:09

I am programming a MFC application in which I have to start another independently developed application on click of a button and continue with my application.
I could use _execv() but the control does not return to my application, until the other application is closed. Is there any other way to do this??

Re: Run an exe from MFC app

Iain Clarke, Warrior Programmer30-Jul-07 4:16

Iain Clarke, Warrior Programmer

30-Jul-07 4:16

Look for 2 API calls:

CreateProcess is the raw win32 one, or you may be better off with ShellExecute (a bit friendler)

Iain.

Re: Run an exe from MFC app

Roberto Italy30-Jul-07 21:12

Roberto Italy

30-Jul-07 21:12

Try to use the standard spawn() family of functions, using
_P_WAIT or _P_NOWAIT
as the 'mode'parameter.

Roberto

Re: Run an exe from MFC app

Hamid_RT31-Jul-07 21:14

Hamid_RT

31-Jul-07 21:14

Does ShellExecute helpful?

WhiteSky

post thread message()

shakumar_2230-Jul-07 3:59

shakumar_22

30-Jul-07 3:59

Hi
In my vc++ 6.0 i used

THREADFUNCTION(WPARAM &wp,LPARAM &lp)
{
CString t_str;
t_str.format("%s",wp);
AfxmessageBox(t_str);
}

i Received the correct out put, here no problem.

I Compiled my programme in Visual studio 2005(vc 8.0)
It shows compile error , so iremoved all "&".
eg :(THREADFUNCTION(WPARAM wp,LPARAM lp) no compile error.

but there was an error in displaying result(its displaying some symbols)

THREADFUNCTION(WPARAM wp,LPARAM lp)
{
CString t_str;
t_str.format("%s",wp); /**** error ***/
AfxmessageBox(t_str);
}

how to convert WPARAM TO STRING in Visua Studio 2005.

Awaiting for the result.

Regards
shakumar

shakumar

Re: post thread message()

Iain Clarke, Warrior Programmer30-Jul-07 4:20

Iain Clarke, Warrior Programmer

30-Jul-07 4:20

Is it a UNICODE thing? I read recently that VC2005 defaults to unicode.

So, if you post the message in ASCII, then your thread function is using it as unicode, then you'll get a bunch of gibberish (if you're lucky).

Have you tried doing:

PostThreadMessage (blah, (WPARAM)_T("My String"), blah)

rather than:

PostThreadMessage (blah, (WPARAM)"My String", blah)

?

Iain.

Re: post thread message()

shakumar_2230-Jul-07 4:38

shakumar_22

30-Jul-07 4:38

Thanks for your Reply

I used String pointer

CString t_str="hai";
CString* p_str;
p_str=new CString (t_str);
PostThreadMessage(WM_USER+100,(WPARAM)p_str,0);

so can i use like this
PostThreadMessage(WM_USER+100,(WPARAM)_T(p_str),0);

regards
shakumar

shakumar

Re: post thread message()

Iain Clarke, Warrior Programmer30-Jul-07 5:06

Iain Clarke, Warrior Programmer

30-Jul-07 5:06

1/ Did you bother trying? If so, you'd have found out the answer which is:

2/ No, and it will hopefully give you an error message when compiling.

What I would do next is to go a bit simpler, and post:

PostThreadMessage (WM_USER + 100, 1234, 5678);

and see if the thread message bit is working properly. If they are, then see what the value of p_str is before you post it, and when it is received. And so on. If that is OK, use the Memory tool of the debugger to see the contents pointed to by p_str.

One thought that occurs to me:

p_str points to a valid bit of memory when you post it. Does it still point to a valid bit later? (ie when the message is received). Is it possible that the CStrings destructor has been called, and the memory is now filled with junk?

Iain.

How to put an MFC Dialog box project into another existing project

vladimir7230-Jul-07 2:29

vladimir72

30-Jul-07 2:29

Can anyone tell me how to put an MFC Dialog box project into another existing project in visual studio C++ 6.o.

Thanks
Vladimir

Re: How to put an MFC Dialog box project into another existing project

Nelek30-Jul-07 2:40

Nelek

30-Jul-07 2:40

Menu "project" option "add to project" and then including whatever you need wherever you need it

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Re: How to put an MFC Dialog box project into another existing project

vladimir7230-Jul-07 2:51

vladimir72

30-Jul-07 2:51

Hello MDV,

That didn't worked. Can you give me an example how to fit a dialog box class into an exisiting project.

Greetings,

Vladimir

Re: How to put an MFC Dialog box project into another existing project

Hans Dietrich30-Jul-07 3:12

Hans Dietrich

30-Jul-07 3:12

Take a look at this.

Best wishes,
Hans

[CodeProject Forum Guidelines] [How To Ask A Question] [My Articles]

Re: How to put an MFC Dialog box project into another existing project

vladimir7230-Jul-07 3:58

vladimir72

30-Jul-07 3:58

It didn't worked. Can you show me an example how you do that?

greetings,

Vladimir

Re: How to put an MFC Dialog box project into another existing project

Nelek30-Jul-07 20:23

Nelek

30-Jul-07 20:23

Ok, First of all take a look on the link Hans Dietrich gave you.

Anyways... what I told you should work, I have added classes to my project and I had no problems. The only thing you have to take care is to create a resource to fit your DialogBox. I mean, you create an empty DialogBox, close it, goes to the file *.rc in the *.cpp path and edit it.

A trick to do this is to look for the name of a resource into all the files of the project, I mean... just added a DialogBox had the IDD_DIALOG1 name, just use this in the search, the results will come where below in "Search in files1" (1st option is the compiler errors, 2nd debug, 3rd "search in files1", 4th search...) Open the ApplicationName.rc file with a doble click there. Then you will see a file with ALL your resources of the active project in code, not in grafics.

Look for your IDD_DIALOG1 (or the name you wanna give to it), erase the contents and replace it with the code of the dialog you wanna import. That will let you to have the new dialog with all the references/names of the old one.

After this, reboot your VC++ and you should have the Dialog in your resources as it is. Doubleclick to create an associated class, remove the new files and add the *.cpp and *.h of the dialog.

The only problem with it is that a DialogBox-based application can have some code that collisionate with the intialisation of a DOC-View app. But is nothing that you can't deal.

Anyways, I have taken a look to Hans Dietrich article and it will work very good, and its "cleaner". What I told you is a "bruto"'s way.

Good luck and have fun Smile | :)

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

re: Fast Searching...

Bryster30-Jul-07 1:54

Bryster

30-Jul-07 1:54

Hi Here is the Problem:

To access a Datafile which contains 26 Million addresses and find a given address. The Datafile is an ascii text file and is fixed

What I have come up with:
1. Sort the 26 Million addresses into Postcode order. (I have application for this)
2. Using FSEEK look at the MIDDLE of the file and compare using STRNCMP the POSTCODE for searching, against the POSTCODE within the Datafile.
3. Using the result move the file pointer backwards from the middle (half it) or forwards and keep checking until a match is found.
This will loop for roughly 24-25 times and not 26 Million.

Is there a better way?

Re: re: Fast Searching...

Randor 30-Jul-07 1:58

Randor

30-Jul-07 1:58

I would recommend converting the text file and using a binary tree for faster searching.

I can think of two libraries you could possibly use to accomplish this:

QDBM
http://qdbm.sourceforge.net/[^]

SQLITE
http://www.sqlite.org/[^]

Best Wishes,
-David Delaune

Re: re: Fast Searching...

Bryster30-Jul-07 2:25

Bryster

30-Jul-07 2:25

Thank you, I will have a look at these. Big Grin | :-D

Re: re: Fast Searching...

Hans Dietrich30-Jul-07 3:17

Hans Dietrich

30-Jul-07 3:17

Probably the easiest way to speed searching is to divide the big file into N smaller files, maybe organized by a partial postcode. Then, after you have selected the correct (smaller) file, the search will be that much faster. This involves a minimum or presort setup.

Best wishes,
Hans

[CodeProject Forum Guidelines] [How To Ask A Question] [My Articles]

Re: re: Fast Searching...

Bryster30-Jul-07 4:12

Bryster

30-Jul-07 4:12

Thank you, that sounds like a good idea.

re: Problems with Progress Bar

Bryster30-Jul-07 1:25

Bryster

30-Jul-07 1:25

Hi I have recently upgraded from Windows 2000 to Windows XP Professional and have noticed that when I run my applications the progress bar stops and the application looks as if it has crashed, but after a while finishes.
I have Mcafee Virus protection running in the background, is this causing the problem?

The code is a simple "UpdateData(FALSE)" instruction after setting the ProgressBar.SetPos() which is looping until an EOF instruction.

Any Ideas?

Thank you in advance

Brian. D'Oh! | :doh:

Re: re: Problems with Progress Bar

Hans Dietrich30-Jul-07 3:21

Hans Dietrich

30-Jul-07 3:21

1. Disable McAfee and observe the result.

2. Put a ProgressBar.RedrawWindow(); after the UpdateData(FALSE); and observe the result.

Best wishes,
Hans

[CodeProject Forum Guidelines] [How To Ask A Question] [My Articles]

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