C / C++ / MFC Discussion Boards

Zdeslav Vojkovic14-Apr-03 4:14

14-Apr-03 4:14

older applications like PopUp utility on Win95 use mailslots (Popup creates mailslot named "messngr", and periodically checks if there are new messages in mailslot. when sending messages, it simply writes to messngr mailslot on another machine)

you can also use messenger service on Win2K and later, but i never used that, so i can't go into details (this is what is used when you issue a command like "net send <machine> hi" at command prompt).

Image Sharing

HardStone14-Apr-03 0:15

HardStone

14-Apr-03 0:15

Hello All,

I want to share HBITMAP bitween 2 applications (IPC) using memory mapped files. but i m getting problems.

anybody can tell me how can i share HBITMAP b/w 2 application ?

thanx in advance.

Unsure | :~

DirectX 9 book

Liorsh14-Apr-03 0:05

Liorsh

14-Apr-03 0:05

Hi.

Anyone knows a good book to start learning DirectX from ?
I mean from a beginner level...
Thanks,
Lior.

The Shell NameSpace Extension AppWizard v3.1

bazoon13-Apr-03 23:24

bazoon

13-Apr-03 23:24

Did anyone use
NSExt.Awx: The Shell NameSpace Extension AppWizard v3.1
written by Krishna Kotipalli for namespace extension. When i try to use in app wizard, the message comes
"App wizard failed to load the custom appwizard 'C:\program files\vstudio\common\msdev98\template\nsext.awx' "

Can any body tell me whats the problem

What is the best Encryption library and where can I get it??

IrishSonic13-Apr-03 22:48

IrishSonic

13-Apr-03 22:48

What is the best Encryption library and where can I get it??

Also where do I find samples on how to use it??

Thanks,
grahamoj.

Re: What is the best Encryption library and where can I get it??

Joaquín M López Muñoz13-Apr-03 22:51

Joaquín M López Muñoz

13-Apr-03 22:51

Don't know if the best, but it is damn good anyway: Crypto++[^] comes with lots of docs and samples, it is totally free and suffers from none of the export restrictions applicable in the US.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

component creation in C++

pankajdaga13-Apr-03 22:47

pankajdaga

13-Apr-03 22:47

Hi everyone,

I am looking for a tutorial that discusses GUI component creation in C++ and packaging it as DLL. Can anyone with some experience point me to a good website or recommend a good book for this.

Thanks,

Sincerely,

Pankaj

Without struggle, there is no progress

Re: component creation in C++

valikac14-Apr-03 7:50

valikac

14-Apr-03 7:50

Do you want a normal MFC DLL or a COM component?

For MFC DLL, here is one good resource.

http://www.mindcracker.com/mindcracker/c_cafe/dll.asp

Kuphryn

Re: component creation in C++

pankajdaga14-Apr-03 22:16

pankajdaga

14-Apr-03 22:16

Hi,

Actually I was looking for a DLL that does not use MFC. Do you know any such component DLL examples?

Thanks for your reply.

Sincerely,
Pankaj

Without struggle, there is no progress

scripting tools to generate C++ file from another C++ file.

smalladi13-Apr-03 22:45

smalladi

13-Apr-03 22:45

hi,
I am a novice to Windows programming. I have been mainly exposed to a unix
environment so far. I need to parse a file to generate a C++ header file
that can be used again the C++ code.

Specifically, I have to generate a function to convert a string value to its enum.

So,
enum numbers = {zero,one, two, three};
numbers temp = StringToEnum("zero"); // StringToEnum() should return the integer 0;

I want to maintain one file for the enum (its really big ) and generate a file
containing the function for StringToEnum()). This new file can then be used to compile
other code. Typically, I would do this by writing a shell script in unix followed by
appropriate changes to the makefile.

I am new to a Windows environment.
Can anyone please tell me how to achieve this in VC++ ( what scripting language,
if at all can I use and if there is any way I can set options to generate the C++
file that contains the function on the fly prior to compilation ).

Thanks and regards,
-sharath.

Sharath.

serveral radio buttons groups on the same dialog

Broker200313-Apr-03 22:36

Broker2003

13-Apr-03 22:36

Hi,

I'm a beginner with VC++ 6.x and I'm becoming crazy. I don't know how to manage several group of radio buttons on the same dialog box... it seems that evey radio buttons are included in the same unique group !

Any ideas ???

thanks !

Re: serveral radio buttons groups on the same dialog

Iain Clarke, Warrior Programmer13-Apr-03 22:48

Iain Clarke, Warrior Programmer

13-Apr-03 22:48

In short, radio buttons are lumped together by their WS_GROUP style.

In the old days, you could do something like:

CheckRadioButton (hDlg, IDC_FIRSTONE, IDC_LASTONE, idCheckedOne);
CheckRadioButton (hDlg, IDC_FIRSTTWO, IDC_LASTTWO, idCheckedTwo);

But you would have to make sure you had non overlapping ids. It was also
a pain to find out which button was set in each group.

You can now use

DDX_Radio (pDX, IDC_FIRSTONE, nCheckOne);
DDX_Radio (pDX, IDC_FIRSTTWO, nCheckTwo);

in your CMyDlg::DoDataExchange method.

To associate buttons in a group together, first make sure every control in
your dialog has the group style bit checked. Then set the tab order (ctrl-d)
so that successive radio buttons have successive order. Last but not least
clear the group style bit for all radio buttons except the first in each
group.

Good luck,

Iain.

Re: serveral radio buttons groups on the same dialog

Broker200313-Apr-03 22:56

Broker2003

13-Apr-03 22:56

That's it ! so hard to find such information in the Visual C++ documentation... it saves me a lot of time !

Many thanks

a doubt ?

Anonymous13-Apr-03 22:32

Anonymous

13-Apr-03 22:32

someobject *var=new someobject[100];
delete var;
----------------
someobject *var=new someobject[100];
var=null;
---------------

what is the difference betn these two statements?

Re: a doubt ?

Xander8013-Apr-03 22:41

Xander80

13-Apr-03 22:41

I'm not sure, but I think that

someobject *var=new someobject[100];
delete var;

frees alocated memory

and

someobject *var=new someobject[100];
var=null;

changes the pointer to null

Re: a doubt ?

Anonymous13-Apr-03 22:47

Anonymous

13-Apr-03 22:47

Does that mean, when the pointer is made null,
the memory it pointed to also gets freed.
can "var=null" be used inplace of "delete var;" ?!!

Re: a doubt ?

Joaquín M López Muñoz13-Apr-03 22:54

Joaquín M López Muñoz

13-Apr-03 22:54

No, as C++ is not garbage collected var=NULL is probably an error and generates a leak in your application. Nobody will take care of the memory you leave behind undeleted. This doesn't necessarily mean a memory leak if var points to some memory block that is also pointed to by some other pointer, and you properly delete that.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: a doubt ?

Iain Clarke, Warrior Programmer13-Apr-03 22:55

Iain Clarke, Warrior Programmer

13-Apr-03 22:55

"var=NULL" is NOT the same as "delete var".

If you imagine that

BYTE *var= new BYTE [100]<pre>
allocates a lump of memory for your use (it may be longer than 100 bytes long) and sets 
var to point to it.

<pre>var=NULL;

simply makes your variable point "nowhere". The memory is still allocated.

delete [] var;

frees the memory, but your variable is still pointing to the now freed patch or memory.
You could still use it, but not safely. Note the [] in the delete command as you
are freeing an array.

You should be doing something like:

BYTE *var = new BYTE [100];    // Allocate some short term memory

...                            // Use it for some purpose

delete [] var;                 // "give it back"
var = NULL;                    // Forget about it so we don't use it my mistake.

Pointers are one of those things you struggle with for a while then wake up one morning
going "Ahah!"

Iain.

Thanks [a doubt ?]

Anonymous13-Apr-03 23:02

Anonymous

13-Apr-03 23:02

Thanks guys!!
That was tremenodus response in no time at all.
You're all great.
Life is so much easier with you.
God Bless All.

Question about raw socket and TCP.

George213-Apr-03 22:10

George2

13-Apr-03 22:10

Hi, everyone!

I want to implement a mini-TCP protocol that can simulate
TCP's three-time shake hands method and simulate simple
"send" and "recv" method in socket programming. I want to
use raw socket but I am not sure whether there are some
alternative methods.

I just want to get simple implementions to make a concept
proof purpose of how TCP is working. Just for learning purpose.
Smile | :)

I want to know whether there are some sample codes of this
topic that I can make a reference? Must I use RAW SOCKET?
Are there some alterative methods or alternative methods?

Thanks in advance,
George

CDialog - change title

LittleYellowBird13-Apr-03 21:55

LittleYellowBird

13-Apr-03 21:55

Hi,

I need to change the title of a dialog box, this is what I have tried:-

<code>
CDlgCal dlgCal(this);
dlgCal.SetWindowText("Step to something");
if(dlgCal.DoModal()==IDOK)
{
blah blah blah .....
}
</code>

But I get this ASSERT error when it runs ....

<b>ASSERT(::IsWindow(m_hWnd));</b>
Any ideas?

Thanks.

Ali

Re: CDialog - change title

Taka Muraoka13-Apr-03 22:09

Taka Muraoka

13-Apr-03 22:09

The window hasn't been created at this point, only the object that will be managing the window.

You need to handle the WM_INITDIALOG message and call SetWindowText() then.

Software is everything. It also sucks. Charles Fishman [^]

Awasu 1.0.2 (beta)[^]: A free RSS reader with support for Code Project.

Re: CDialog - change title

Cedric Moonen13-Apr-03 22:10

Cedric Moonen

13-Apr-03 22:10

Yes it's because your window doesn't exist when you call the SetWindowText function. It's better to change the text in the OnInitDialog() overloaded member function.

Re: CDialog - change title

peterchen13-Apr-03 22:12

peterchen

13-Apr-03 22:12

You have to do the SetWindowText inside the OnInitDialog (or later)...

The problem with Modal Windows dialogs is the Win32 Window is created & destroyed in DoModal(), i.e. it does not exist before the call.
Since MFC is supposed to be a "light wrapper", it doesn't do the same level of abstraciton as .NET or (shudder) VB.

"Der Geist des Kriegers ist erwacht / Ich hab die Macht" StS

sighist | Agile Programming | doxygen

Re: CDialog - change title

Rage13-Apr-03 22:12

Rage

13-Apr-03 22:12

The assertion comes because you try to set the text before the dialog is created with DoModal(), so the dialog has no handle, and the API function fails.

To do it properly, go in the CDlgCal::OnInitDialog() (Override the WM_INITDIALOG message if you do not have that function present in the class browser), and put your code in this function. i.e. :

... CDialog::OnInitDialog(...bla...)
{
...    
 SetWindowText("Step to something");
...
}

~RaGE();

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