C / C++ / MFC Discussion Boards

Re: Does CSocket class support databases

prithaa6-Feb-07 5:50

6-Feb-07 5:50

Hello,

Yes, I understood what you said.But how do I read data from the database and put in the structure. For doing this which topics should I cover.

Thanks nave
Prithaa

Re: Does CSocket class support databases

Mark Salsbery6-Feb-07 8:03

Mark Salsbery

6-Feb-07 8:03

prithaa wrote:
I have use CRecordSet class to read and write to a database on a single PC

If you have done that then, depending on the database server you are using, you can adjust your
CDatabase connection settings to access a database server on a network. Then the communication
is done for you.

Otherwise you need to do all your database access in your server app, and handle the transfer of
data (possibly using sockets) to/from the client(s).

Two possible methods.

Mark

Re: Does CSocket class support databases

prithaa6-Feb-07 8:37

prithaa

6-Feb-07 8:37

Hello,
thanks

So, I should go through CSocket class for client/server support for database access?

or CDatabase will work for the connections purpose once proper Host String or IP address is given .
I don't know what an IP address means but if that is the address of the server which has to be given at the client side.

Prithaa

Re: Does CSocket class support databases

Mark Salsbery6-Feb-07 9:16

Mark Salsbery

6-Feb-07 9:16

I think it depends on the system you are developing, how it will be used, how scaleable you want
it, what the database system provides, how many concurrent users, etc.

Some advantages of writing your own server between the clients and the database server are:

Direct control over security - can provide encryption for plain-text over the network

Direct control over database connections - For example, connection pooling can be implemented to
reduce the number of server seat/connection licenses required.

I would suggest searching for articles and studying the difference between 2-tier database
connectivity (client-database) and 3-tier connectivity (client-server-database). Here's one
example: Multi Tier Architectures for Database Connectivity[^]

If you choose to do your own client-server communication then definitely study sockets -
especially if don't know what an IP address means. Sockets know nothing about the data you
are transferring. Sockets just provide the endpoints for the connection. You'll need to
come up with a scheme for transferring data that both ends understand.

Windows Sockets 2[^]

Mark

memory leak in ADO Connection & Excute methods

voorugonda prashanth5-Feb-07 21:45

voorugonda prashanth

5-Feb-07 21:45

Hi All,

please suggest me how to avoid memory leak ADO.

Re: memory leak in ADO Connection & Excute methods

Roger Stoltz5-Feb-07 23:03

Roger Stoltz

5-Feb-07 23:03

voorugonda prashanth wrote:
please suggest me how to avoid memory leak ADO.

Free the memory you've allocated? Unsure | :~

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

Re: memory leak in ADO Connection & Excute methods

#realJSOP5-Feb-07 23:15

#realJSOP

5-Feb-07 23:15

If I voted messages, I'd give you a five. Of course, I'd also like to add that he should consider other employment opportunities after that kind of question...

"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001

Re: memory leak in ADO Connection & Excute methods

Roger Stoltz5-Feb-07 23:17

Roger Stoltz

5-Feb-07 23:17

John Simmons / outlaw programmer wrote:
Of course, I'd also like to add that he should consider other employment opportunities after that kind of question...

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

Exception in VC++ Code.

T.RATHA KRISHNAN5-Feb-07 21:27

T.RATHA KRISHNAN

5-Feb-07 21:27

I have created a Visual Studio.NET 2003 project using MFC. It's a gaming project. If I execute this project a window opens. After completing all the gaming operations,if I close the window, an exception occurs stating that

'Unhandled exception at 0x7c918fea in Perspective.exe: 0xC0000005: Access violation writing location 0x00000010.'

This exception occurs under both Debug and Release modes.

When I break this exception, it goes to a class free.c which is not created by me.

How to resolve this exception?

Re: Exception in VC++ Code.

prasad_som5-Feb-07 21:31

prasad_som

5-Feb-07 21:31

As error says, its due to access violation. And that is due to your code.
Can you post relevent code ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Exception in VC++ Code.

kakan5-Feb-07 21:35

kakan

5-Feb-07 21:35

Follow the call stack until you find a function that you wrote. And there you will find the cause of the problem.

Alcohol. The cause of, and the solution to, all of life's problems - Homer Simpson

Re: Exception in VC++ Code.

Michael Dunn5-Feb-07 22:36

Michael Dunn

5-Feb-07 22:36

When you get a crash when accessing location 0 or something near 0, it means you're dereferencing a null pointer.

--Mike--
Visual C++ MVP Cool | :cool:

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Re: Exception in VC++ Code.

Hamid_RT6-Feb-07 0:11

Hamid_RT

6-Feb-07 0:11

I think your problem is of pointers.

WhiteSky

Re: Exception in VC++ Code.

ThatsAlok6-Feb-07 19:55

ThatsAlok

6-Feb-07 19:55

T.RATHA KRISHNAN wrote:
Unhandled exception at 0x7c918fea in Perspective.exe: 0xC0000005: Access violation writing location 0x00000010.'

you tried to called something on NULL pointer without providing it memory

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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assigning string value to CDBVariant

prithaa5-Feb-07 21:23

prithaa

5-Feb-07 21:23

Hello,

How do I assign a value to an object of type CDBVariant?Especially if the data type is string.

CDBVariant b;
CString str;
b.m_dwtype = DBVT_STRING;
b.m_pstring = str;

but in the union of CDBVariant m_pstring is pointer to string.so what has to be done?

Thanks
Pritha

Re: assigning string value to CDBVariant

prasad_som5-Feb-07 22:52

prasad_som

5-Feb-07 22:52

prithaa wrote:
b.m_pstring = str

Pass address of string.

CDBVariant b;
CString str;
b.m_dwtype = DBVT_STRING;
b.m_pstring = &str;

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: assigning string value to CDBVariant

prithaa5-Feb-07 23:44

prithaa

5-Feb-07 23:44

Hello,

So I need to maintain the CString variable so that the pointer has a meaning .I cannot destroy the the CString object or create the object locally ? i.e

Thanks for your reply Prasad
Prithaa

Re: assigning string value to CDBVariant

prasad_som6-Feb-07 0:33

prasad_som

6-Feb-07 0:33

True.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: assigning string value to CDBVariant

Naveen6-Feb-07 0:49

Naveen

6-Feb-07 0:49

prithaa wrote:
b.m_pstring = str;

instead use

b.m_pstring = new CString(str);

the destructor of the CDBVariant will delete this newly created CString.

nave

Convert DWG/BMP image file to PNG image format

helpcode5-Feb-07 20:39

helpcode

5-Feb-07 20:39

Hi,
I am developing a application in which i need to convert the .DWG/.BMP image files into PNG image file format. Can anybody help me to this in VC++ ?
Thanks in Advance !!

Jiteen

Re: Convert DWG/BMP image file to PNG image format

Hamid_RT5-Feb-07 20:54

Hamid_RT

5-Feb-07 20:54

See http://www.wotsit.org[^] for info about graphic files.If you want to save file you can read bmp or png(not dwg)file with CImage class and use of CImage::Save but for dwg I think you need to lot of work.;)

WhiteSky

Re: Convert DWG/BMP image file to PNG image format

helpcode6-Feb-07 0:33

helpcode

6-Feb-07 0:33

Thanks a lot sir !!

Jiteen

Re: Convert DWG/BMP image file to PNG image format

Hamid_RT6-Feb-07 0:51

Hamid_RT

6-Feb-07 0:51

You're welcome Wink | ;)