Object reference not set to an instance of an object. - C / C++ / MFC Discussion Boards

Rajesh R Subramanian22-Dec-09 23:42

22-Dec-09 23:42

OK you modified that post. While I thought the EM_REPLACESEL itself was a great idea, I wouldn't have liked the usage of GetDlgItem() call. But hey, different people, different ways. (why I don't like GetDlgItem()? Because I'm a terrific fan of Dr. Joseph Newcomer, and his philosophies and I take 'em seriously).

Added: Look at my second answer to the OP. Smile | :)

“Follow your bliss.” – Joseph Campbell

modified on Wednesday, December 23, 2009 5:48 AM

Re: Reg - Edit Box

KingsGambit22-Dec-09 23:52

KingsGambit

22-Dec-09 23:52

Me too don't like to use GetDlgItem(). It is always better and clean to use binded members with DDX/DDV. I thought I would provide an answer which resembles the sample code segment in the post Smile | :)

. Thanks for the comment.

Re: Reg - Edit Box

LunaticFringe23-Dec-09 6:33

LunaticFringe

23-Dec-09 6:33

Rejeesh.T.S wrote:
Me too don't like to use GetDlgItem(). It is always better and clean to use binded members with DDX/DDV.

You do realize, of course, that DDX_ macros internally call GetDlgItem? Newcomer's screed on the subject overlooks that fact. It really comes down to personal preference in coding style; one way is no more evil than another. Personally I try to avoid MFC-specific API's where possible - it makes porting code between frameworks a little less painful.

L u n a t i c F r i n g e

Re: Reg - Edit Box

Rajesh R Subramanian22-Dec-09 23:21

Rajesh R Subramanian

22-Dec-09 23:21

Use a control type member variable for the edit control. Then do something like

m_Edit.GetWindowText(szTemp );
szTemp += _T("Whatever");
m_Edit.SetWindowText(szTemp);

“Follow your bliss.” – Joseph Campbell

Re: Reg - Edit Box

Rajesh R Subramanian22-Dec-09 23:48

Rajesh R Subramanian

22-Dec-09 23:48

Hi,

You might want to try this (thanks to Rejeesh for his EM_REPLACESEL suggestion, which triggered this idea)

int len = m_Edit.GetWindowTextLength(); //find the length of text in the control
m_Edit.SetSel(len, len, 0);     //select nothing (but the cursor goes to the end)
m_Edit.ReplaceSel(szNewText);   //new text will be printed at the end now!

“Follow your bliss.” – Joseph Campbell

Re: Reg - Edit Box

KingsGambit22-Dec-09 23:54

KingsGambit

22-Dec-09 23:54

This is the MFC way. Now the code looks cleaner Smile | :)

Re: Reg - Edit Box

Paulraj G23-Dec-09 0:27

Paulraj G

23-Dec-09 0:27

Sorry for deleyed reply...

Thanks for Both of you...

the problem has been solved...

G.Paulraj

Object reference not set to an instance of an object.

Anu_Bala22-Dec-09 22:29

Anu_Bala

22-Dec-09 22:29

After converting my project from VC6.0 to VS2008.Im getting continouly error.I dont have error in building the exe.
When im running this exe i got lot of errors.Mostly on System.AccessViolation,System.NullRefernceException like this.Now i get

An unhandled exception of type 'System.NullReferenceException' occurred in InstructorStation.exe

Additional information: Object reference not set to an instance of an object.

error in this fucntion.

void CMainFrame::UpdateOprs(CTrans *pData)
{
IsNewOpr = TRUE;
WriteDebug("UpdateOprs() - Begin");
.
.
}

THis function get called as follow
CTrans tData;
CMainFrame* tFrm = (CMainFrame*)AfxGetMainWnd();
for(i=0;i<LiveDataCount.Count;i++)
tData.m_sData.Insert(i,LiveArray[i]);
tFrm->UpdateOprs(&tData);

Whats the problem in converting?I thought converting project should be simple likethat.I don't know whether i did any wrong?
Pls guide me on this issue.

Anu

Re: Object reference not set to an instance of an object.

Adam Roderick J22-Dec-09 23:07

Adam Roderick J

22-Dec-09 23:07

CMainFrame* tFrm,
what is the value of tFrm?
Did u check whether it is 0 or not?

Please check

if( 0 != frm )

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Re: Object reference not set to an instance of an object.

Anu_Bala22-Dec-09 23:23

Anu_Bala

22-Dec-09 23:23

While debugging,when i keep mouse on tFrm,it shows as undefined value.

Anu

Re: Object reference not set to an instance of an object.

Adam Roderick J22-Dec-09 23:27

Adam Roderick J

22-Dec-09 23:27

Please change your optimization in project settings to see the value of the variable.

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Re: Object reference not set to an instance of an object.

Anu_Bala22-Dec-09 23:33

Anu_Bala

22-Dec-09 23:33

Sorry,what can i change?
properties->configuratio properties->c/c++->optimization->optimization: Custom
Shall i change to Fulloptimization(/Ox)

Anu

Re: Object reference not set to an instance of an object.

Anu_Bala22-Dec-09 23:59

Anu_Bala

22-Dec-09 23:59

Now i use tFrm as follow

CMainFrame* tFrm;
	tFrm = new CMainFrame();

now that problem is not coming.

Anu

running time

danzie22-Dec-09 21:46

danzie

22-Dec-09 21:46

Hi. I need a program solving the running time of depth first search algorithm..I'm trying to solve it but its hard for me to come up with the solution.
Is it possible to integrate the backtracking in breadth first search algorithm?
If so, can you give me any program for this with computation of its running time ??

I really appreciate any response to this..

Thnx.. Confused | :confused:

Re: running time [modified]

Adam Roderick J22-Dec-09 22:08

Adam Roderick J

22-Dec-09 22:08

Dear friend, this forum is to help to solve your technical problem, no one is here to spoon feed you.
So don't ask for the whole program again in this forum.
And please read the the instruction, how to ask questions [^]
Please check with this link, it will help you related to DFS [^]

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modified on Wednesday, December 23, 2009 4:19 AM

Re: running time

Alan Balkany23-Dec-09 4:19

Alan Balkany

23-Dec-09 4:19

The running time of the depth first search algorithm is O(n) where n is the number of nodes in your graph.

Breadth-first search avoids backtracking, and also has a running time of O(n).

You can find programs for both of these algorithms through Google.

brother and sister, can you help me?

nenfa22-Dec-09 21:24

nenfa

22-Dec-09 21:24

my questions:

how to implement draging for the system icons,just like My Computer,My Document and etc, into other directories in my own design app.as i know,exploer just create a icon-link for the operations,how can i emulate this operation, thank you very much.

your little brother

Re: brother and sister, can you help me?

Adam Roderick J22-Dec-09 21:41

Adam Roderick J

22-Dec-09 21:41

Do u want to get drag and drop of files into your application?

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Re: brother and sister, can you help me?

nenfa23-Dec-09 0:07

nenfa

23-Dec-09 0:07

i want to create a shortcut for my computer in my own application

Re: brother and sister, can you help me?

sashoalm23-Dec-09 0:27

sashoalm

23-Dec-09 0:27

See How to Implement Drag and Drop Between Your Program and Explorer[^]

There is sufficient light for those who desire to see, and there is sufficient darkness for those of a contrary disposition.
Blaise Pascal

Re: brother and sister, can you help me?

rp_suman23-Dec-09 8:59

rp_suman

23-Dec-09 8:59

You can use ShellExecute Function with "Open" as command.

Using SHGetFolderLocation Function you can get the path for special folders you want, and pass that to ShellExecute Function.
Above function seems deprecated, look for equivalent new function.

--
"Programming is an art that fights back!"

MSMQ: Problem with qInfo->PathName setting

PankajB22-Dec-09 20:51

PankajB

22-Dec-09 20:51

Hi There.

My problem is:

I am able to send messages to the queue using my machines name, but am unable to do the same with IP Add.
For example:

qInfo->PathName = "MYCOMPUTER\\private$\\PanBQueue"; works fine...
qInfo->PathName = "IP ADDRESS\\private$\\PanBQueue"; Fails...

Thanks
PanB

Re: MSMQ: Problem with qInfo->PathName setting

Adam Roderick J22-Dec-09 21:42

Adam Roderick J

22-Dec-09 21:42

Did you check the error you are getting?
Please check that first?

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Re: MSMQ: Problem with qInfo->PathName setting

PankajB22-Dec-09 22:08

PankajB

22-Dec-09 22:08

I do not get any error message as such. But when I try to open the queue...i.e.,

qDest = qInfo->Open(MQ_SEND_ACCESS, MQ_DENY_NONE);

I got an exception. Please let me know, in case you need any further details.
Thanks anyway for your effort.

Re: MSMQ: Problem with qInfo->PathName setting

Adam Roderick J22-Dec-09 22:12

Adam Roderick J

22-Dec-09 22:12

Please tell me whats the exception?
And i hope u checked the getLastError [^]

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