C / C++ / MFC

Re: Help! My App crashes and I've no idea why!

14-Aug-01 7:35

Your heap gets corrupted. One of the reasons could be writing past the end of memory block allocated by new or malloc. Do you have any diagnostic tools, like BoundsChecker or Purify?

Tomasz Sowinski -- http://www.shooltz.com

14-Aug-01 22:03

sadly, no I haven't.

Not sure _how_ the heap could be corrupted? like i said, the view class does pretty much nothing at the moment.

CArchive, Serializing & Schema

Jason Teagle14-Aug-01 5:50

14-Aug-01 5:50

I have a situation where I need to serialize several parts of a document-derived class. Because the standard doc loading / saving mechanism is not quite what I need, I have to construct the CArchive manually. All the serialization is working fine in itself, but the one thing I can't seem to get to work now I need it is the schema business.

My doc-derived class uses IMPLEMENT_SERIAL() with the current schema number correctly. I create the archive correctly and then start serializing out (when saving, this is)... but for some reason it never saves the schema in the binary file. I tried SetObjectSchema() immediately after constructing the CArchive, which certainly sets the internal schema value... but that never gets written to file.

I looked at the code for CDocument where it calls our overriden Serialize() to see how it did it - from that I see it sets the archive's m_pDocument and another member. So I did this also... STILL doesn't save the schema in the file.

Since CDocument::Serialize() does not do anything, calling the base class has no effect.

Any clues as to what I'm missing? Otherwise I'll have to do the schema bit myself. But I'd rather use the built-in stuff as much as possible.

Tomasz Sowinski14-Aug-01 6:01

14-Aug-01 6:01

How are you serializing document members? Using m_foo.Serialize(ar) or ar << m_pFoo?

Tomasz Sowinski -- http://www.shooltz.com

Jason Teagle14-Aug-01 6:11

14-Aug-01 6:11

Everything is done using ar << m_pFoo (no objects other than CString are serilaized - most of what is saved is structures, and I do the members of each by hand).

You sound as if you're hinting that each object (class) has its own schema... which I can understand... but should there not be an overall schema for the document / doc-derived object? It does, after all, have IMPLEMENT_SERIAL()...

Basically, I'm not interested in the individual schemas of each thing I serialize - all serializing is done from one class (the doc-derived) (since there are no child objects being serialized, not even CXXXArrays). I want one overall schema that is used in all serializing operations so that I can check it on loading to avoid loading new data from old-schema files...

Jason Teagle14-Aug-01 6:12

14-Aug-01 6:12

Tomasz Sowinski14-Aug-01 6:27

14-Aug-01 6:27

Schema number is written to file only if you use CArchive::WriteObject (operator << for CObject pointers calls this method). WriteObject uses CArchive::WriteClass for sort of 'metadata' (class name, schema version).

Default serialization implemented in CDocument::OnSaveDocument uses plain Serialize. This means that you can't call GetObjectSchema to get document schema number in CYourDoc::Serialize - it's not in the file.

You've mentioned that you're creating CArchive yourself - if you're replacing OnSaveDocument you can also try to replace CYourDoc::Serialize() with ar << pDoc.

Tomasz Sowinski -- http://www.shooltz.com

Jason Teagle14-Aug-01 6:36

IHTMLEditHost in combination with CHtmlView

14-Aug-01 6:36

An excellent suggestion - I will try that trick tomorrow and let you know. Thanks for the help.

CreateIpForwardEntry

Martijn14-Aug-01 5:46

Martijn

14-Aug-01 5:46

I've got a problem with the post SP4 NT4+ API "CreateIpForwardEntry". I'm trying to add a routing rule in the piece of code hereunder. It works just fine. However, if i use the IP address assigned to my ethernetcard as het "next hop" (thereby making it the default gateway for the particular network segment) it fails me. Can anyone help me out?

<br />
	PMIB_IPFORWARDROW pRow = NULL;<br />
	ULONG dwSize = 0;<br />
	DWORD dwStatus = 0;<br />
	<br />
	// Allocate some memory to store the row in<br />
	pRow = (PMIB_IPFORWARDROW)malloc(sizeof(MIB_IPFORWARDROW));<br />
<br />
	if (!pRow) {<br />
		MessageBox("Malloc failed, Out of Memory!\r\n");<br />
		exit(1);<br />
	}<br />
	<br />
	// changing dwForwardNextHop into anything else works...<br />
	// 172.31.64.9 the ip address assigned (through DHCP) to my ethernetcard.<br />
	// route add 172.0.0.0 mask 255.0.0.0 172.31.64.9 metric 30 if 2<br />
	// works just fine.<br />
	pRow->dwForwardDest = inet_addr("172.0.0.0");<br />
	pRow->dwForwardNextHop = inet_addr("172.31.64.9"); // --> this doesn't work, any other value does<br />
	pRow->dwForwardMask = inet_addr("255.0.0.0");<br />
	pRow->dwForwardIfIndex = 2;<br />
	pRow->dwForwardType = 4;<br />
	pRow->dwForwardProto = MIB_IPPROTO_NETMGMT;<br />
	pRow->dwForwardAge = 0;<br />
	pRow->dwForwardMetric1 = 30; <br />
<br />
	// Create a new route entry for the default gateway.<br />
	dwStatus = CreateIpForwardEntry(pRow);<br />
	<br />
	if (dwStatus == NO_ERROR)<br />
		MessageBox("Route Added Successfully\n");<br />
	else if (dwStatus == ERROR_INVALID_PARAMETER)<br />
		MessageBox("Invalid Parameter\n");<br />
	else <br />
		DisplayErrorMessage(dwStatus);<br />
	<br />
	// Free resources<br />
	if (pRow)<br />
		free(pRow);	<br />

Juergen Woelke14-Aug-01 4:35

Juergen Woelke

14-Aug-01 4:35

Hi,

I am trying to implement an edit host (IHTMLEditHost).
I looked at the ATL example, and tried to implement the IServiceProvider interface in the CHtmlView class. But this doesn't work.
The interface function QueryService is not called after activating the editor (spDoc->put_designmode(L"On").
Does anyone have any idea how to do this?

Thanks,

Jurgen Wolke

Socket receive performance

sato14-Aug-01 3:51

sato

14-Aug-01 3:51

I'm using a CAsyncSocket object to communicate with a unix socket server. The performance of the client data reception is too low. It takes about 400 miliseconds between the net ACK and the data catches the OnReceive() callback function. There's no traffic in the net. How can I improve this performance ? In a windows socket server, the problem doesn't occur.
Thanks !
Visual C++ 6.0, Windows98/NT.

sato

Socket receive performance

sato14-Aug-01 3:49

sato

14-Aug-01 3:49

Dockable application needed !

14-Aug-01 3:39

I need my application to be like "Quick Launch" so I could dock it to any screen border or nest in a tray. The GUI consists of a toolbar with a few buttons.
Any ideas?

Thanks!

Re: Dockable application needed !

Paul A. Howes14-Aug-01 4:02

Paul A. Howes

14-Aug-01 4:02

There are two ways of approaching this:

The more common way is provide your application with an icon in the system notification area. When the user clicks on the icon, you can pop-up a menu or a toolbar with the choices you would like the user to have.

The potentially "more correct" way would be to make a deskband for your product. This is actually an extension provided by Internet Explorer and the Active Desktop. If you are running Windows 2000 or ME, or an older version of Windows with the Active Desktop installed, you will notice that you not only have a taskbar, but you can have toolbars, and address bar, and several other bars displayed. Each of these is a deskband which provides some interactive functionality.

The major difference between the two methods is that creating a deskband requires some COM programming. If you are familiar with COM, this should not be an issue. However, there are still many programs out there, such as the ones installed by many video card manufacturers, that add an icon to the system notification area with a pop-up menu.

I hope this helps!

--
Paul

"I drank... WHAT?"

adding binary files

lina14-Aug-01 3:39

lina

14-Aug-01 3:39

Hi I need to binary combine two files from C++ code.
I need to add binary file1 and file2 into file3, which is possible by the following command line:
copy /b a:\test1.txt + a:\test2.txt a:\test3.txt

How can I add those file in C++ code or perform a call to the command line which will perform the copy itself?

thanks,
lina

Re: adding binary files

C^hris L^osinger14-Aug-01 4:03

C^hris L^osinger

14-Aug-01 4:03

there are dozens of fun ways to do this.

the first, like you say, is to just issue a command line command to do it. see the "spawn" function.

the second, C, way to do it is like this:
(off the top of my head, so you'll have to fix any bugs by yourself)

FILE *fp1 = fopen("a:\\test1.txt", "rb");
FILE *fp2 = fopen("a:\\test2.txt", "rb");
FILE *fp3 = fopen("a:\\test3.txt", "wb");

while (!feof(fp1))
{
   BYTE c;
   c = fgetc(fp1);
   fputc(fp3, c);
}

while (!feof(fp2))
{
   BYTE c;
   c = fgetc(fp2);
   fputc(fp3, c);
}
fclose(fp1);
fclose(fp2);
fclose(fp3);

of course this is horribly inefficient. you'd be much better reading and writing large chunks (4K chunks, for example) instead of single bytes (see fread and fwrite).

then there are the C++ ways to do it, with CFile, or the io stream stuff.

all of it is 100% fun.

-c

------------------------------
Smaller Animals Software, Inc.
http://www.smalleranimals.com

Global data problems/can't access variable

14-Aug-01 3:15

In CMainFrame I want to access m_Grid that I have declared global in a CFormView derived class called CTableView. In CTableView I have the declaration:
CMSFlexGrid m_Grid;
But when I for example call m_Grid.GetRows() in CMainFrame I get an error:
'm_Grid' : undeclared identifier..........

What am I doing wrong?, it is another way to access m_Grid from CTableView without making it global?

OyS

Re: Global data problems/can't access variable

#realJSOP14-Aug-01 3:58

#realJSOP

14-Aug-01 3:58

1) First, you have to have a pointer to the view that contains the m_Grid variable. To get one, enumerate through the document templates, and then through the opened documents in each template, and then through the opened views of each document until you get a pointer to the desired view.

2) If the m_Grid variable is not declared public (and it shouldn't be), you either need to make it public, or (better choice) make a public function in your view class that returns the number of rows in the grid.

Re: How to get the pointer to the view

14-Aug-01 21:49

Thanks for your interest. Could you please give me an code example of how I get the pointer to the view. That would be very helpful.

OyS

Re: How to get the pointer to the view

#realJSOP15-Aug-01 1:43

#realJSOP

15-Aug-01 1:43

Have you checked the articles on this web site yet?

Re: How to get the pointer to the view

Bret Faller15-Aug-01 10:06

Bret Faller

15-Aug-01 10:06

If you want a quick and dirty way to get a pointer to your view you can do this:

MainFrm.h:
CMyView* m_pMyView;

MyView.cpp (in OnInitialUpdate):
((CMainFrame*)(AfxGetMainWnd()))->m_pMyView = this;

Make sure to put class CMyView; above your MainFrame class declaration in MainFrm.h

Bret Faller
Odyssey Computing, Inc.

Re: Global data problems/can't access variable

Carsten Kemper5-Nov-01 13:09

Carsten Kemper

5-Nov-01 13:09

Create an instance of your Class CTableView in CMainFrame
..
CTableView tv;
..
access it by typing tv.*

CaKe

How to make an automatically resizable dialogbar

Kiddxin14-Aug-01 0:36

Kiddxin

14-Aug-01 0:36

Hi,

I am adding an automatically resizable dialogbar into my MFC program. But it can not automatically resize when the window size is changed. Can you tell me the reason and how to implement this? Thanks in advance.

Smile | :)

Kidd

Re: How to make an automatically resizable dialogbar

Tomasz Sowinski14-Aug-01 0:48