C / C++ / MFC Discussion Boards

Re: How to check if flash Active x is already installed ?

rahul.kulshreshtha14-Mar-10 20:07

rahul.kulshreshtha

14-Mar-10 20:07

Thanks! That worked.

How could I change the width of a CMFCRibbonButton or CMFCRibbonLabel

A&Ms12-Mar-10 19:15

A&Ms

12-Mar-10 19:15

Is there any way to change the width of CMFCRibbonButton or CMFCRibbonLabel

socket programming

trioum12-Mar-10 18:10

trioum

12-Mar-10 18:10

I am new in socket programming . I made a simple chat client server in sdk(not mfc) . but my GUI hangs
.how can I solve my problem .

Trioum

Re: socket programming

Rajesh R Subramanian12-Mar-10 19:24

Rajesh R Subramanian

12-Mar-10 19:24

There can be many reasons. How can we assume things without knowing the details of it?!

This guide might help you if you're starting out with Network programming: http://beej.us/guide/bgnet/[^]

“Follow your bliss.” – Joseph Campbell

Re: socket programming

«_Superman_»13-Mar-10 17:17

«_Superman_»

13-Mar-10 17:17

You probably have some blocking socket calls in your UI thread.
Some of the blocking socket calls are accept, recv etc.
You will need to create separate threads in which you can put these blocking calls.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Changing Edit box colour on button click

learningvisualc12-Mar-10 17:13

learningvisualc

12-Mar-10 17:13

Hi all,

I want to change colour of my edit box on button click ...... how can i do this...

Thanks in advance

Re: Changing Edit box colour on button click

R@jeev K R12-Mar-10 19:02

R@jeev K R

12-Mar-10 19:02

Try this...

SendMessage(m_hWnd, EM_SETBKGNDCOLOR, 0, RGB(0, 255, 255)

Thumbs Up | :thumbsup:

Re: Changing Edit box colour on button click

«_Superman_»13-Mar-10 17:21

«_Superman_»

13-Mar-10 17:21

Handle the WM_CTLCOLOREDIT message in the parent dialog and return the necessary colored brush.
Since you want to do this on a button click, in the button click event handler, set a flag and then call UpdateWindow for the edit control. In the WM_CTLCOLOREDIT message handler you can check this flag before returning the colored brush.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

SHIFT+F3

johnalek12-Mar-10 12:19

johnalek

12-Mar-10 12:19

Hi

How we code for combination of keys like SHIFT+F3

#sanroop#

Re: SHIFT+F3

Gwenio12-Mar-10 12:52

Gwenio

12-Mar-10 12:52

Depends on the program. Are you using a window? If so, then when you get key up/down (which ever is more appropriate) event for F3, use the following code to test if the shift key is up or down:

if (GetKeyState(VK_SHIFT) < 0) /*do stuff*/;

Notes:
VK_SHIFT is equal to 16.
The test is to see if the high order bit is set.

There are other ways of doing this, but you need to give more information so that we can determine what would work best.

Re: SHIFT+F3

Rajesh R Subramanian12-Mar-10 18:38

Rajesh R Subramanian

12-Mar-10 18:38

If it were to be done system-wide, you'll need to install a keyboard hook. But you *do* have to provide more details. Please read the how to get an answer to your question sticky on top of the first page of this forum.

“Follow your bliss.” – Joseph Campbell

Re: SHIFT+F3

Code-o-mat12-Mar-10 23:07

Code-o-mat

12-Mar-10 23:07

For a system wide hot key he can also use RegisterHotKey[^].

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Re: SHIFT+F3

Rajesh R Subramanian13-Mar-10 3:32

Rajesh R Subramanian

13-Mar-10 3:32

Thanks, but I'm not the one who needs to know it. It may have helped if you had replied to the OP.

“Follow your bliss.” – Joseph Campbell

Re: SHIFT+F3

Code-o-mat13-Mar-10 5:58

Code-o-mat

13-Mar-10 5:58

Oups, sorry, yeah, i even wanted to do that but by the time i submitted it to you i completely forgot about it. Thanks for reminding me. Thumbs Up | :thumbsup:

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

Re: SHIFT+F3

Code-o-mat13-Mar-10 5:59

Code-o-mat

13-Mar-10 5:59

For a system-wide hotkey you can use RegisterHotKey[^].

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

permutations12-Mar-10 8:33

permutations

12-Mar-10 8:33

I have a problem in my program that I don't know how to even begin to track down. Please help!

It's an MFC program compiled in Visual Studio 2008 for WinXP and above (WinVer=0x0501). It runs fine for everyone who has tested it except one person who is running WinXP SP3. He's tried it on two different computers running WinXP SP3 and it crashes on both. I'm pretty sure he's the only one with SP3. I have XP SP2 here and it runs fine.

It crashes at the Windows entry point - the call to _tWinMain in crt0.c (which I know through the crash.dmp file he sent me):

            mainret = _tWinMain( (HINSTANCE)&__ImageBase,<br />
                                 NULL,<br />
                                 lpszCommandLine,<br />
                                 StartupInfo.dwFlags & STARTF_USESHOWWINDOW<br />
                                      ? StartupInfo.wShowWindow<br />
                                      : SW_SHOWDEFAULT<br />
                                );<br />
<br />
<br />

The error message says: "Unhandled exception at 0x0041505e (myprog.exe) in CRASH.DMP: 0xC0000005: Access violation reading location 0x00000004."

I don't know how to even begin to track down a problem like this, especially when it appears to be platform-specific. Could someone give me some guidance on how to go about this?

Thanks!!!!

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

Bram van Kampen12-Mar-10 8:57

Bram van Kampen

12-Mar-10 8:57

Hi,

I sympathise! The best way I can think of, is to get a separate machine with XpSp3 on it, and single step through it with a debugger. (you can also make your own system dual boot.) All you need is 'Bare Bones', with the Compiler, and your Files.

The bug appears to be in the Startup code. See if it does the same with a trivial MFC program. Also, after the Debug Version is Fixed (On your SP2 Machine!!) Test if the Retail version behaves, on BOTH SP2 and SP3 machines.

Things to look out for: It appears that either '__ImageBase' or 'lpszCommandLine' ended up being 0x04. You probably end up single stepping from 'wmainCRTStartup'.

Success,

Smile | :)

Bram van Kampen

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

permutations12-Mar-10 9:47

permutations

12-Mar-10 9:47

Bram van Kampen wrote:
The best way I can think of, is to get a separate machine with XpSp3 on it, and single step through it with a debugger. (you can also make your own system dual boot.) All you need is 'Bare Bones', with the Compiler, and your Files.

I'd like to do that, but I'm running out of computers to put test code on. I used to have two XP notebooks, but one of them is dying - it makes a very loud grinding noise - and none of my machines has the hard disk space for dual booting.

Do you know at what point in an MFC program the _tWinMain function is called? If I could know how much of my code is executed - at what point in my program the deadly call is made - it would be a huge help. I'm just not that adept with the more exotic aspects of the debugger so I don't know how to figure this out.

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

Bram van Kampen13-Mar-10 0:54

Bram van Kampen

13-Mar-10 0:54

Hi,

permutations wrote:
I'd like to do that, but I'm running out of computers to put test code on.

well, That's somewhat essential if you support code spanning different O'S'. I have a dedicated Desktop machine with several harddisks, which I can boot up on anything from Xp Standard to Win7. The machine cost me less than £100 in a carboot sale. It 'Runs' vista, but just about. (a Lot happier with Win7). It is not ideal as a recommended environment for a customer, but it does exactly do the things I want to trap, i.e. incompatibilities.

permutations wrote:
Do you know at what point in an MFC program the _tWinMain function is called?

Just start debugging by pressing F10. The program will break at _tWinMain. Then in your Stack window, go to the Calling Routine, and scroll to the top where you find _WinMainCRTStartUp(). Set a breakpoint there, and start again. That code will call set up the libraries and call the constructors.

Smile | :)

Bram van Kampen

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

permutations13-Mar-10 3:57

permutations

13-Mar-10 3:57

I broke down and did it. I don't have a lot of computers, but I do have a lot of spare hard drives, it turns out. I forgot about that.

I still cannot reproduce the bug, even under XP SP3. Also, two more beta testers turned up with XP SP3 and they can't, either. I think it's something this other guy is running. I asked him to try disabling his startup programs. It may be a bug in something else he's running that's writing beyond the boundaries of its own memory.

Also, I have VC++ 6 installed now on the XP SP3 system, and I'm going to rebuild the project there with line numbers in the map file. That will tell me exactly the line that is causing the problem.

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

Bram van Kampen13-Mar-10 9:19

Bram van Kampen

13-Mar-10 9:19

permutations wrote:
I broke down and did it

It's not that serious I hope... OMG | :OMG:

permutations wrote:
I still cannot reproduce the bug, even under XP SP3. Also, two more beta testers turned up with XP SP3 and they can't, either

Bugs like that can be tricky to find. An added problem is that seems to occur before WinMain starts. Things like Dumpfiles probably won't work! Things to look out for are your global variables. Are they all propperly initialised! If not, your program may work most of the time because the variable has a value that is by coincidence acceptable (or at least does not cause a crash). Change Something, (anything at all), and Oops! Crash!.

permutations wrote:
two more beta testers turned up with XP SP3 and they can't, either

That seems to be a good omen!

Success,

Smile | :)

Bram van Kampen

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

C^hris L^osinger12-Mar-10 9:01

C^hris L^osinger

12-Mar-10 9:01

couple of things to look for:

1. initialization of global variables (especially classes which do non-trivial things in their ctors).

2. are you loading any DLLs? are they doing anything non-trivial in their WinMain's ?

also, i ran into a similar problem when i apparently got a bit too aggressive with pre-compiled headers. i had moved everything i could think of into the PCH, and for some reason, this caused the ctor of a global std::list variable to explode on startup. i never could track down exactly why it was happening, so i simply turned off PCH for that configuration and it worked fine.

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Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

permutations12-Mar-10 9:41

permutations

12-Mar-10 9:41

Chris Losinger wrote:
2. are you loading any DLLs? are they doing anything non-trivial in their WinMain's ?

Yes, there is a very significant DLL. Here's a little bit more about what I'm doing. I wrote a DOS program back in 1991 that got some good reviews and sold pretty well. I wanted to rerelease this for both Windows and the Web, but without completely rewriting the thing. So I separated out all the DOS interface stuff, and created what I call the "engine", which I can then access from any interface.

Using precompiler directives, I can compile the engine as a DLL (called from my MFC interface), a CGI (compiled for Linux on the server) and accessed through HTML, or a standalone console app with no interface (I hardcode the values for testing).

In my InitInstance procedure, I find the user's My Documents directory, make a subdirectory beneath that for the files the app creates, then call a function in the DLL called BuildFileNames(). This basically takes some standard filenames and prepends the path that I found in InitInstance. I have stepped through this whole thing with the debugger and it is working correctly.

When I return from that, I initialize some global variables that I export in the DLL, open a database file (or create an empty one, if it does not exist), add the database file to the MRU list, and then display the app's main window.

The app uses a modeless dialog for the main window. I wrote a class called ModelessMain, which was easier than trying to circumvent the doc/view architecture.

One of my difficulties in tracking down the problem is that I don't know at what point it's crashing, from the perspective of my own code. The crash is in the _tWinMain() procedure, and I don't know at what point that is called. Isn't it called before InitInstance() even executes? And if so, how can my own code be causing this crash?

My difficulty here is my lack of understanding of how my MFC program is eventually calling the function that fails - the stack of calls from my program to eventually the failure point. That's why I don't even know where to look in my own code.

I really appreciate any help you can give me because I'm dead in the water at this point. I simply don't have the first clue how to proceed. I read something somewhere about looking at the stack of calls to figure this out, but I don't know how to do these advanced debugging techniques.

Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

C^hris L^osinger12-Mar-10 9:59

C^hris L^osinger

12-Mar-10 9:59

permutations wrote:
The crash is in the _tWinMain() procedure, and I don't know at what point that is called. Isn't it called before InitInstance() even executes?

tWinMain calls AfxWinMain (in fact, that's all it does, in the MFC source that comes with VS08 ), and AfxWinMain eventually ends up calling your app's InitInstance.

extern "C" int WINAPI
_tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
	_In_ LPTSTR lpCmdLine, int nCmdShow)
#pragma warning(suppress: 4985)
{
	// call shared/exported WinMain
	return AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
}

so, i doubt the problem is in tWinMain itself. the problem has to be farther down the line.

if you can't reproduce the problem on your own machine, you can try something like a map file[^]. or, there's always good old log files[^].

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Re: crash in _tWinMain, crt0.c, XP SP3 only - HELP!!

permutations12-Mar-10 10:13

permutations

12-Mar-10 10:13

Chris Losinger wrote:
tWinMain calls AfxWinMain (in fact, that's all it does, in the MFC source that comes with VS08 ), and AfxWinMain eventually ends up calling your app's InitInstance.

This is another one of my points of confusion. In the crash.dmp file the beta tester sent me, the crash pops up inside the source file crt0c. The call looks similar to the one you quote, but not exactly. When I step into my app, I see what you quoted here. It's from appmodule.cpp. I tried to trace this through but it never got to this mysterious crt0.c call, which is slightly different. I also cannot figure out why the program would be calling _tWinMain TWICE in different modules.

Furthermore, if _tWinMain is called BEFORE my InitInstance function, then how could anything in my InitInstance function be the cause of the crash?

Chris Losinger wrote:
so, i doubt the problem is in tWinMain itself. the problem has to be farther down the line.

I don't understand. How can code farther down the line, that hasn't executed yet, be the cause of the crash? There are fundamental things I don't understand about how MFC/Windows work that hamper my ability know where to look.

Chris Losinger wrote:
if you can't reproduce the problem on your own machine, you can try something like a map file[^]. or, there's always good old log files[^].

Very interesting article about what to do with a map file, thanks. I've been creating a map file with exports, but had no idea what to do with it.

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