Re: Using Semaphore - C / C++ / MFC Discussion Boards

Re: platform specific API or C standard API

George_George11-Nov-07 23:11

George_George

11-Nov-07 23:11

Thanks gleat,

You are so cool.

regards,
George

How to check that ADO connection is successfully open or not.

CodingLover11-Nov-07 19:25

CodingLover

11-Nov-07 19:25

Hi all,

I've create a ADO connection to connect a SQL database to my application as follows.

<br />
	ADODB::_ConnectionPtr pConn;<br />
	ADODB::_RecordsetPtr pRecSet;<br />
<br />
	GetADOCon( srf_SQL, pConn, pRecSet );<br />
	sqlStr.Format( "SELECT * FROM RecordData" );<br />
	hr = pRecSet->Open( _bstr_t(sqlStr), pConn.GetInterfacePtr(), ADODB::adOpenDynamic, ADODB::adLockOptimistic, -1);<br />

It works fine on my application. But I want to avoid future issues that opening the database/dataset and check it is exist or not.

How can I do that.

Can I use SUCCEED to assert my application.

Thanks.

I appreciate your help all the time...
Eranga Smile | :)

Re: How to check that ADO connection is successfully open or not.

CodingLover11-Nov-07 21:18

CodingLover

11-Nov-07 21:18

I've done it simply as follows.

<br />
		if (FAILED(hr))<br />
		{<br />
			AfxMessageBox( "Open Database connection Failed." );<br />
		}<br />

How far this way is efficient to use.

I appreciate your help all the time...
Eranga Smile | :)

Re: How to check that ADO connection is successfully open or not.

Rajasekharan Vengalil11-Nov-07 22:41

Rajasekharan Vengalil

11-Nov-07 22:41

From the code snippet you posted earlier I gather that you are using #import to import the ADO type declarations. Depending on what attributes you used while writing your #import statement the HRESULTs returned by COM methods might be swallowed by the wrapper class that the compiler generates for you (in the ".tli" file) and get translated into C++ exceptions throwing _com_error objects. So you might want to handle that exception.

--
gleat
http://blogorama.nerdworks.in[^]
--

Re: How to check that ADO connection is successfully open or not.

CodingLover11-Nov-07 22:47

CodingLover

11-Nov-07 22:47

Of course, yes. I've already wrote few classes to handle that exception. Smile | :)

Actually that my question is part of a error handling class. Big Grin | :-D

I appreciate your help all the time...
Eranga Smile | :)

Using Semaphore

narayanagvs11-Nov-07 19:09

narayanagvs

11-Nov-07 19:09

Hi,

I have a Pdf file which I want to run from my Application.

I want to restrict copy access to a file when I open the file using the my application.

Can I restrict access to that Pdf file by placing a lock on that file? So that only my application accesses it and no one can access the file.Is that a possible Solution?

Any Suggestions would be helpful.

Thanks

Today is a gift, that's why it is called the present.

Re: Using Semaphore

Naveen11-Nov-07 19:45

Naveen

11-Nov-07 19:45

narayanagvs wrote:
when I open the file using the my application.

Through which API ur opening the file? Another applications, such as explorer cannot copy a file if it is already opened with the share deny ready permission.

Check the "DWORD dwShareMode" parameter in the CreateFile() API.

nave

[OpenedFileFinder]

Re: Using Semaphore

Cedric Moonen11-Nov-07 20:18

Cedric Moonen

11-Nov-07 20:18

narayanagvs wrote:
Can I restrict access to that Pdf file by placing a lock on that file? So that only my application accesses it and no one can access the file.Is that a possible Solution?

You mean using a semaphore ? If that's the case, then the answer is no. A semaphore has to be used by all parties that want to access a resource (whatever it might be). So, in all the programs that wants to access the resource, they need to use the same semaphore.
If you lock your file in your application through a semaphore, nothing prevent explorer (for example) to open the file (because it doesn't use a semaphore to open the file).

Cédric Moonen
Software developer

Charting control [v1.2]

Re: Using Semaphore

narayanagvs12-Nov-07 0:55

narayanagvs

12-Nov-07 0:55

Cedric Moonen wrote:
You mean using a semaphore ? If that's the case, then the answer is no

If not semaphores, Is there any way to do that?

Thanks

Today is a gift, that's why it is called the present.

Re: Using Semaphore

JudyL_MD12-Nov-07 2:07

JudyL_MD

12-Nov-07 2:07

When you open the file, use the exclusive flag. As Cedric said, semaphores have nothing to do with this.

Judy

Need some clarification

Mushtaque Nizamani11-Nov-07 19:05

Mushtaque Nizamani

11-Nov-07 19:05

Hi,
when I compiled this code

if ( testvar == 10 )<br />
    strTestVar = "Test1";<br />
else<br />
    strTestVar = "Test2";

Then compiler prompt me the error "illegal else without matching if", but when I changed the code to

if ( testvar == 10 )<br />
{<br />
    strTestVar = "Test1";<br />
}<br />
else<br />
{<br />
    strTestVar = "Test2";<br />
}

then code compiled successfully.

Can any one please explain why is it so?

Best Regards,
Mushq

Mushtaque Ahmed Nizamani
Software Engineer
Ultimus Pakistan

Re: Need some clarification

Hamid_RT11-Nov-07 19:46

Hamid_RT

11-Nov-07 19:46

Maybe you used of two statements in if without {} or use of two elses.

Re: Need some clarification

Llasus11-Nov-07 19:51

Llasus

11-Nov-07 19:51

is the code inside some other if's? the code compiles on mine correctly (VS2005). just included the declaration of the 2 variables used.

Image scaling

Deepu Antony11-Nov-07 18:53

Deepu Antony

11-Nov-07 18:53

Can any body help me to scale an image of size=307*257 (BMP 8 bit grayscale) to size=157*157

Thanks in advance

Re: Image scaling

Hamid_RT11-Nov-07 19:11

Hamid_RT

11-Nov-07 19:11

See StretchBlt.

Re: Image scaling

Hamid_RT11-Nov-07 19:36

Hamid_RT

11-Nov-07 19:36

And see CPJAImage - Yet another image drawing class[^].

Re: Image scaling

Llasus11-Nov-07 19:47

Llasus

11-Nov-07 19:47

what do you do with the image anyway? do you load to your program and display it? as suggested by Hamid you can use StretchBlt, or in LoadImage there is already a setting there to set a desired size for you image.

Re: Image scaling

Deepu Antony11-Nov-07 20:34

Deepu Antony

11-Nov-07 20:34

i already have the image pixel array as a two dimensional matrix in my program.i just want to resize it to the desired form.

Re: Image scaling

Llasus11-Nov-07 21:10

Llasus

11-Nov-07 21:10

Is your output going to be a resized two dimensional array? Or you only need to resize its the image (no need for the matrix to be resized)?

If you are going to resize the two dimensional matrix, what I can only think of is to load the image to a CDC handler (through SetPixel), resize it (using StretchBlt), and use the GetPixel to pass the pixel data to a new resized matrix. This though will take some time (if the image is very large).

If you only need the image to be resized, you can use the StretchBlt after setting the pixels to the CDC handler.

Re: Image scaling

Deepu Antony12-Nov-07 3:06

Deepu Antony

12-Nov-07 3:06

Thanks it works.Thanks a lot

Exception in socket programming

gReaen11-Nov-07 18:51

gReaen

11-Nov-07 18:51

Hello everyone

I'm doing a single client server application.

After receiving a file from the client, server gets closed with the following exception.

Debug assertion failed!
Program: path of file
File: winhand.cpp
Line: 229

But the file is getting transferred correctly. And i need to send more than one file without connection being closed.

Plz help...

Re: Exception in socket programming

Llasus11-Nov-07 19:30

Llasus

11-Nov-07 19:30

First use GetLastError() to check the error number and find out what the exact problem is. It may be in either application which closes the socket after receiving/sending. Or it can be possible that the socket was declared locally inside a function, that's why on exit the socket is released. Try GetLastError first to check the error code. Smile | :)

Also you should put some checking on the returns of the socket functions to check if the function was successful, otherwise it wouldn't have been generating assert errors like that, just failure to do the functions correctly.

Re: Exception in socket programming

Hamid_RT11-Nov-07 19:34

Hamid_RT

11-Nov-07 19:34

See Network Transfer Of Files Using MFC's CSocket Class[^] if helpfuls.

Flag for Protected system files?

bholoo11-Nov-07 18:38

bholoo

11-Nov-07 18:38

Hello to every body,
IShellFolder::EnumObjects(.....) In this method, if we pass
"SHCONTF_INCLUDEHIDDEN" then it includes hidden items for enumeration, but there is no flag for "Protected System Files". What should I do if I want "system files" to be included for enumeration as well?
Thanks in anticipation.
Best Regards,
Yasir Nisar

CTreeCtrl and undo/redo

Hans Dietrich11-Nov-07 18:33

Hans Dietrich

11-Nov-07 18:33

Does anyone know of a CTreeCtrl-derived class that supports undo/redo of operations like move, copy, delete?

Best wishes,
Hans

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