Weird memory issue - C / C++ / MFC Discussion Boards

Csaba Csata10-Nov-05 5:10

10-Nov-05 5:10

Hy.My problem is i dont know how to make gif animation in dynamic way with CxImage.
I found a static solution in the MFC demo program,but i need a dynamic one,
to allocate the memory dynamic.
thanx the help

Using database and recordsets with multiple .mdb files.

Mark F.10-Nov-05 4:50

Mark F.

10-Nov-05 4:50

Hi All,

I have a small app that is designed to open an Access database file (.mdb) from a normal CFileDialog. Each database has one table and has the exact same fields in it. My question is how can I open a CDatabase and connect to the CRecordset with any of the database files I select? When I created the new CRecordView and CRecordset a blank default .mdb file was used via ClassWizard.

If the default sql string is empty the "Select Database" dialog appears, but I want to select a database from my apps menu handler.

I have a CRecordView derived class (CEditorView) that will edit (add, delete, etc) the records. Unfortunately, most of the tutorials are for "reading" records only.

Hope this make sense. Thanks.
Confused | :confused:

Mark

Re: Using database and recordsets with multiple .mdb files.

hairy_hats10-Nov-05 5:33

hairy_hats

10-Nov-05 5:33

Take a look at this for classes to allow you to read and write to databases. There are also examples on how to edit records.

Re: Using database and recordsets with multiple .mdb files.

Mark F.10-Nov-05 6:14

Mark F.

10-Nov-05 6:14

Thanks, but I am using ODBC:CRecordset/CDatabase for this app.

Mark

Re: Using database and recordsets with multiple .mdb files.

David Crow10-Nov-05 8:54

David Crow

10-Nov-05 8:54

Mark F. wrote:
My question is how can I open a CDatabase and connect to the CRecordset with any of the database files I select?

You'll want to use a DSN-less connection. This article shows a brief example.

Mark F. wrote:
I have a CRecordView derived class (CEditorView) that will edit (add, delete, etc) the records. Unfortunately, most of the tutorials are for "reading" records only.

Editing/adding/deleting is no big deal. Just use CRecordset's methods. For example:

rs.m_pDatabase->BeginTrans();
TRY
{
    rs.Open();
    rs.AddNew();
    rs.var1 = 123;
    rs.var2 = "Name";
    ...
    rs.Update();
    rs.m_pDatabase->CommitTrans();
}
CATCH(CDBException, pDBException)
{
    rs.m_pDatabase->Rollback();
}

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: Using database and recordsets with multiple .mdb files.

Mark F.11-Nov-05 10:15

Mark F.

11-Nov-05 10:15

David,

I will read the article you posted. Thanks for the help!

Smile | :)

Mark

DirectX - How to Create Virtual Video Capture Source using the Filter

Vishal Jariwala10-Nov-05 4:15

Vishal Jariwala

10-Nov-05 4:15

Hi,
I need a virtual 'Video Capture Source'. I could make use of DirectX Filter to create a video capture source. But i am not getting how it is implemented in VC++. Can any example or link provide way to Register Filter created in VC++ as 'Video Capture Sources'

Thanks,

Jariwala Vishal

-- modified at 23:28 Thursday 10th November, 2005

Weird memory issue

Axonn Echysttas10-Nov-05 4:00

Axonn Echysttas

10-Nov-05 4:00

Hi everybody. I stumbled today on a rather intriguing issue. I got a DLL which is loaded via a hook in Explorer.exe. In that DLL I got the following HFONT array.

#pragma bss_seg("Share")<br />
<br />
HFONT *hfntarrLabels;<br />
<br />
#pragma bss_seg()

I need it in a #pragma 'cause I use another application to set its elements. Anyway... the problem is that when I try to clean it up, free the memory, explorer.exe crashes. This is how I create it, before hooking:

hfntarrLabels = new HFONT[10];<br />
hfntarrLabels[0] = CreateFont(...)

And this is how I free it, during the hooking:

delete []hfntarrLabels; // <-- crashes

And this, also crashes:

SelectObject(hdcMem, hfntarrLabels[0]);

Even though as far as I can see, the hfntarrLabels[0] has a non zero value.

Ideas anybody?

-= E C H Y S T T A S =-
The Greater Mind Balance

Re: Weird memory issue

S. Senthil Kumar10-Nov-05 4:55

S. Senthil Kumar

10-Nov-05 4:55

Axonn Echysttas wrote:
hfntarrLabels = new HFONT[10];
hfntarrLabels[0] = CreateFont(...)

From the code, it looks like you are allocating memory in one process and trying to access it from another. If that's the case, it's not going to work, since each process has its own virtual address space and an address in one is meaningless to another.

Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro

Re: Weird memory issue

Axonn Echysttas10-Nov-05 6:24

Axonn Echysttas

10-Nov-05 6:24

But I'm using #pragma. Wasn't that supposed to fix such issues? Sorry, I'm a bit of a beginner in this memory allocation business ::- D. Anyway... I tried at least 10 combinations and it crashes and crashes and crashes all the time. I'm going nuts here ::- (. Explorer.exe just won't let me delete (free) an array I created before and crashes. Even if I created it from my DLL Loader process, it's still the same DLL right? It gets attached to Explorer.exe.

-= E C H Y S T T A S =-
The Greater Mind Balance

Re: Weird memory issue

S. Senthil Kumar10-Nov-05 19:02

S. Senthil Kumar

10-Nov-05 19:02

I'm no expert in #pragma directives, but a quick Google search showed that

#pragma data_seg("SHARED")

is the right way to share *data* between applications loading the same DLL.

Axonn Echysttas wrote:
Even if I created it from my DLL Loader process, it's still the same DLL right? It gets attached to Explorer.exe.

It's the same DLL, but it gets mapped to different address spaces everytime it's loaded by a process. In short, a memory addresses are specific to a process, so calling new in one process and delete on the other will definitely result in a crash.

Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro

How to remname a VC++ project

TUMB10-Nov-05 3:54

TUMB

10-Nov-05 3:54

Can some one tell me steps to be taken to rename a project.

Re: How to remname a VC++ project

Axonn Echysttas10-Nov-05 4:12

Axonn Echysttas

10-Nov-05 4:12

As far as I remember, for VC++ 6 Rename your DSW file and your DSP file. If the environment asks you for the location of the DSP file upon loading the DSW, simply browse for it and then save all files. For .Net, might be the same but I'm not sure. You might need to rename the cppproj file. Hope that helps.

-= E C H Y S T T A S =-
The Greater Mind Balance

Re: How to remname a VC++ project

Robin Hilliard10-Nov-05 6:59

Robin Hilliard

10-Nov-05 6:59

Assuming your project name is "blah", open up BLAH.DSP and BLAH.DSW in your favourite text editor and go to the first line on the DSP file, which will look like:

# Microsoft Developer Studio Project File - Name="blah" - Package Owner=<4>

Then do a global + all files search'n'replace for the string "blah" with the name of your new project (let's try "halb"). Save and exit. Then rename BLAH.* to HALB.* at the command prompt (you *are* using a good one like 4NT, aren't you? Smile | :)

) and away you go. Take 20 seconds and works.

_vsnprintf questions

ita_cas10-Nov-05 2:35

ita_cas

10-Nov-05 2:35

HI all ,
Are there any restrictions (size wise) when using this function
my bouncechecker screams when the size of the sent buffer is greater then 6648 bytes

anyone ?

thanks

Re: _vsnprintf questions

toxcct10-Nov-05 2:46

toxcct

10-Nov-05 2:46

ita_cas wrote:
bouncechecker

what's that ?

looking at the MSDN[^], i cannot see any restriction of this type...
maybe you overrun your buffer ?!

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: _vsnprintf questions

kakan10-Nov-05 3:21

kakan

10-Nov-05 3:21

He means BoundsChecker, a tool manily used for checking memory usage in an application.
BoundsChecker has saved me more than once... Big Grin | :-D

Re: _vsnprintf questions

toxcct10-Nov-05 3:28

toxcct

10-Nov-05 3:28

ok, i just didn't know it...

TOXCCT >>> GEII power
[toxcct][VisualCalc]

srvice modeRun Project in Service mode

thelip200510-Nov-05 0:48

thelip2005

10-Nov-05 0:48

Hi This is Fresh programer in VC++ ,So can any one give me a brief discription , how to write a code to make it run in service mode..

Dilip

Re: srvice modeRun Project in Service mode

thelip200510-Nov-05 1:15

thelip2005

10-Nov-05 1:15

come on some one reply me please..... Roll eyes | :rolleyes:

Dilip

Re: srvice modeRun Project in Service mode

kakan10-Nov-05 1:51

kakan

10-Nov-05 1:51

Search for the word "service" in the articles here at CP.

And/or look at these articles:
http://www.codeproject.com/system/xyntservice.asp[^]

http://www.codeproject.com/system/cntservice.asp[^]

http://www.codeproject.com/system/serviceskeleton.asp[^]

Kakan

name of the device

viliam10-Nov-05 0:07

viliam

10-Nov-05 0:07

I am trying to obtain a file path from handle in Windows NT driver. The PFILE_OBJECT->FileName contains only the path such as "\directory\file.ext" but not the device name or drive letter. How do i obtain the device name (drive letter) for the file?

I think there could be a way throught the PFILE_OBJECT->DeviceObject, but can't dig out from the DDK documentation how to get the name of this device.

Thanx

viliam

How to scroll text ?

Amarelia10-Nov-05 0:02

Amarelia

10-Nov-05 0:02

Hi
I want a MFC application in which I want to scroll some text. Also sometime text might be long and sometimes it might be short. Also Font size of text might need to be as big as 200. So is there a way to do it ?

I tried using CBannerStatic example given in this site, but problem occurs when i make my text size big. It stops scrolling and consumes 100% CPU making other application work very very slow.

So I want to make it myself and text shold scroll smothly without any flickering.....is there a way to do this ?

Thankx a lot in advance

Amarelia Maehsh
Gujarat
India

Re: How to scroll text ?

toxcct10-Nov-05 0:08

toxcct

10-Nov-05 0:08

still on the same problem since more than one month ?! Confused | :confused:

TOXCCT >>> GEII power
[toxcct][VisualCalc]

Re: How to scroll text ?

S Douglas10-Nov-05 1:38

S Douglas

10-Nov-05 1:38

I have used this one AIM-Style Scrolling Banner Control
[^]and found it to work fairly well.

Either way, why note dissect the code locate the problem and let the author know. Most authors seem to enjoy others helping them with their projects.

DEBUGGING : Removing the needles from the haystack.

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