C / C++ / MFC Discussion Boards

Rajkumar R6-Mar-08 2:23

6-Mar-08 2:23

I think both are same explicit specialization as if you define both, induce redefinition error, literally, the former template argument is deduced while the later template argument is specified.

Re: template function instantiation

George_George6-Mar-08 15:11

George_George

6-Mar-08 15:11

Thanks Rajkumar,

I have got the redefinition error as you pointed out. Cool! But to use the latter one, it is also not mandatory needed to specify the template parameter type, it could also be deduced. Here is my code to prove. Any comments?

#include <iostream>

using namespace std;

void g(int a){	cout << a << endl;}

template <class T> void f(T a) {	g (a);}

// template <> void f(int a) {	g (a);}

template <> void f <int>(int a) {	g (a);}

int main()
{
	f (100);

	return 0;
}

regards,
George

iterator for deque

George_George5-Mar-08 22:00

George_George

5-Mar-08 22:00

Hello everyone,

As mentioned in Gotw about deque. What means "streamlined version of deque with simplified iterators"? I did some search and can not find out.

http://www.gotw.ca/gotw/054.htm

--------------------
Finally, note that the popular library implementation that I tested has since been revised and now includes a streamlined version of deque with simplified iterators. I do not yet have a copy of that library, but it will be interesting to see how much of the deque disadvantage in even the raw iterator "traverse" and element-accessing "at" tests will remain compared to vector.
--------------------

thanks in advance,
George

Re: iterator for deque

Maximilien6-Mar-08 1:00

Maximilien

6-Mar-08 1:00

it simply means there is a STL library somewhere that even Sutter does not yet have (at the time of the writing) contains a streamline version of the dequeue container and simplified iterator.

streamline means better (either in performance and/or in memory useage).
simplified means, well, more simple than the current implementation (I assume the current one is not simple)

I also assume that you know that the "Guru Of The Week" #54 is nearly 19 years old (written in 1999) and that there have been lots of improvements in STL and that what he was writing about is probably already included in the current STL implementation and that there are no "non" streamline or "non" simplified versions of dequeue.

you could try to get a copy of the dequeue code from that time and compare it with the current code to see what have changed.

Maximilien Lincourt
Your Head A Splode - Strong Bad

Re: iterator for deque

George_George6-Mar-08 16:26

George_George

6-Mar-08 16:26

Thanks Maximilien!

1.

What is your point? The Gotw #54 is out of date?

2.

I want to learn your comments about what do you think are possible improvements? compare with traditional implementation of deque? Currently, I only know traditional way of implementing deque -- chunks and chunks containing elements. Smile | :)

regards,
George

Selecting a folder from open dialog ????????

TooShy2Talk5-Mar-08 21:40

TooShy2Talk

5-Mar-08 21:40

Hi,

I just want to ask how can i select folder in file open dialog?
Because it usually enters a folder when i select it.
Is it possible?

If not what should i use and how will i do it?

Thank you.

Re: Selecting a folder from open dialog ????????

Rajkumar R5-Mar-08 21:48

Rajkumar R

5-Mar-08 21:48

SHBrowseForFolder() ?

Re: Selecting a folder from open dialog ????????

James R. Twine6-Mar-08 5:30

James R. Twine

6-Mar-08 5:30

   You can do this by adding another button to the dialog template ([Select] for example), and when clicked you can return the path(s) to the selected item(s).

   Lookup customizing the common file dialog for more information on how to specify a custom dialog template and react to actions taken in it.

   Peace!

-=- James
Please rate this message - let me know if I helped or not!<hr></hr>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles

Problem in Release Mode please look at the code.

ritz12345-Mar-08 21:38

ritz1234

5-Mar-08 21:38

Hello friends,

Please find the following code that creates the problem in release mode and run well in debug mode.I am using VC 6.0.

<
#include "win.h"//this file contains the declarations of the classes

#define ID_TIMER1 1

BEGIN_MESSAGE_MAP(MyWin,CFrameWnd)
END_MESSAGE_MAP()

MyWin::MyWin()
{
Create(NULL,"Test");
}

BEGIN_MESSAGE_MAP(App,CWinApp)
ON_WM_TIMER()
END_MESSAGE_MAP()
BOOL App::InitInstance()
{

m_pMywin=new MyWin();
m_pMainWnd=m_pMywin;
m_pMainWnd->UpdateWindow();
m_pMainWnd->ShowWindow(SW_SHOWNORMAL);

::SetTimer(NULL,ID_TIMER1,5000,NULL);

return TRUE;
}
void App::OnTimer()
{
AfxMessageBox("App Timer");
}
App obj;
>

ritz1234

Re: Problem in Release Mode please look at the code.

Roger Stoltz5-Mar-08 22:59

Roger Stoltz

5-Mar-08 22:59

First of all: debug your application!
This is essential if you want help from others. You will be asked questions about the results from your debugging sessions and if you cannot answer those questions, you cannot be helped. An explanation like "it crashes" is always wrong unless followed by an explanation about how it crashes.

More on the problem:
In my opinion you're using the timer API in an unusual way by having the application class handle the WM_TIMER message. Having your window class setting up the timer and handle its events would be more straight forward. I'm not saying that it's impossible, because it's not, but if you're less experienced with MFC and message handling you'd be better off by choosing a main stream solution.
You should also read the documentation carefully; calling ::SetTimer() with the hWnd param set to NULL makes the function return the ID of the timer. It could be a new ID that you're supposed to use when calling ::KillTimer(), but you simply ignore it.

You also have to verify that the problem actually is related to the timer. In your previous thread you mention something about multiple threads and a web cam that may also have something to do with this.
Now I'm just guessing, but it could be a plausible cause: you have an ActiveX control that receives input from the web cam and you're trying to access it from another thread than the one that created the control without proper marshalling.

To help you further, whether it would be me or anyone else, you have to debug your application and tell us how it fails.
If you're only having troubles in the release version, then build the release version with debug info. There are more differences between building release mode and debug mode than just creating the debug info.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Re: Problem in Release Mode please look at the code.

ritz12345-Mar-08 23:27

ritz1234

5-Mar-08 23:27

Hi,thanx for the reply,

Right now forgot about the previous posts.

This is the sample test application which also fails believe me.

If you want then try it out.

It crashes in release mode as following.

When I run the application in release mode the OnTimer function gets

executed and then after it crashes with dialog to send the error report

to microsoft with the "send" and "Don't send" buttons.

The win.h file on the above code snippest has the following code

class MyWin:public CFrameWnd
{
public:

MyWin();

DECLARE_MESSAGE_MAP()
};

class App:public CWinApp
{
public:

MyWin *m_pMywin;

BOOL InitInstance();

afx_msg void OnTimer();

DECLARE_MESSAGE_MAP()
};

ritz1234

Re: Problem in Release Mode please look at the code.

Maxwell Chen6-Mar-08 1:24

Maxwell Chen

6-Mar-08 1:24

I copied your code to make a SDI project with VC++ 2005. There are some issues.

First of all, the prototype of OnTimer is not what you wrote. The correct one is:

afx_msg void CWnd::OnTimer(UINT_PTR nID);

OnTimer is a member function of CWnd. And Your App class is of the base CWinApp, which is not CWnd.

And Secondly, your this line doesn't compile at all.

BEGIN_MESSAGE_MAP(App, CWinApp)
  ON_WM_TIMER()
END_MESSAGE_MAP()

The reason is as mentioned above: OnTimer is a member function of CWnd, not of CWinApp. Therefore static_cast is not allowed.

Maxwell Chen

Re: Problem in Release Mode please look at the code.

Roger Stoltz6-Mar-08 1:37

Roger Stoltz

6-Mar-08 1:37

Ok, in other words:
You have a serious design flaw in your application. You're using the SDK version of SetTimer() since SetTimer() is not defined in CWinApp. When using MFC you would usually do this in a CWnd derived class since SetTimer() is defined in the CWnd class.

Using the ON_WM_TIMER macro is very wrong in your case, since it assumes the class to be a CWnd subclass and you're using it from a CWinApp subclass. On top of that the message handler you provide as a parameter to ON_WM_TIMER must be declared as
afx_msg void OnTimer( UINT nIDEvent );. You have omitted the parameter which will, at the best, corrupt the stack frame.

Like I wrote earlier, it's possible to use a timer in the app class, but chances that this is really what you want to do are ridiculously close to zero depending on how the MFC framework is intended to be used.

I recommend you to stay within the MFC classes for doing basic stuff like this.
If you want to start the timer when the application start, you should declare a message handler for the WM_CREATE message and override the CWnd::OnCreate() member function. From your message handler you can call CWnd::SetTimer(). Use the wizards for this and don't forget to add a message handler for WM_TIMER as well and override CWnd::OnTimer().

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

Re: Problem in Release Mode please look at the code.

ritz12346-Mar-08 17:12

ritz1234

6-Mar-08 17:12

Hi, thanx Roger and Maxwell.

I also realize that I should not use the timer for the application class

because they can be used by the CWnd derieved class. So I change the code

of the application and I use timer in class derieved from CMDIFrameWnd.

So the problem is solved now.

Thanks for the help once again.

ritz1234

vertical text

Russell^'5-Mar-08 21:23

Russell^'

5-Mar-08 21:23

I need to write a text line vertically and at the same time the font must have every char displayed with the same width (like courier, or like the font used in VS editor to let us move vertically along the columns) (hope be clear).
Now:
If I use Courier Font I get the right font...but it seems uncompatible with the nEscapement parameter to write the text vertically.
If I use Tahoma the nEscapement parameter is well imported, but the space between the char is not constant.
Cry | :((

So
How can I find a font that let me use both this properties?...Is there some property that I can check?
Of course...only using the standard fonts that Windows user has got by default.
Thanks a lot Unsure | :~

Russell

Re: vertical text

Rajkumar R5-Mar-08 21:29

Rajkumar R

5-Mar-08 21:29

Not sure, But why not let the CreateFont() pick the font which matches the characteristics?

Re: vertical text

Russell^'5-Mar-08 21:37

Russell^'

5-Mar-08 21:37

I am using CreateFont....but not every font type understand the Escapement parameter...I'm trying every font right now... I'm going crazy Big Grin | :-D

Russell

Re: vertical text

Rajkumar R5-Mar-08 21:45

Rajkumar R

5-Mar-08 21:45

Russell' wrote:
I'm trying every font right now

I think you are setting the font name in the "lpszFace"

"If lpszFace is NULL or empty string, GDI uses the first font that matches the other specified attributes" from msdn.

Re: vertical text [SOLVED]

Russell^'5-Mar-08 21:59

Russell^'

5-Mar-08 21:59

Courier New math both the required.
Plus:
To have constant spacing with every font must be set both lfHeight and lfWidth!!!. So you can also use many other fonts (compatible with the lfEscapement parameter)more then Courier New.

But a little problem remains:
One time that the font writes in vertical way the size of the text it is not perfecly rotated (there is a little stretch) ... propably because the pixels are not squared, but rectangular. (any trick?)

Bye bye

Russell

libs

duta5-Mar-08 21:07

duta

5-Mar-08 21:07

hi there
i've made an application which use a lib.

how can i build an executable file, without deliver the dll's.

how can i know which files have to be near the executable?

Re: libs

Hamid_RT9-Mar-08 1:09

Hamid_RT

9-Mar-08 1:09

Do you want to know wwhich files your program is used?

Save and retrive data from Database

Rupesh Kumar Swami5-Mar-08 20:45

Rupesh Kumar Swami

5-Mar-08 20:45

hi,
i am beginner to visual c++ . so i have no idea that how can i store & Retrive data in databse using visual C++(Not MFC).
Anybody have idea that from which point i start.
i am very thankful if anybody give me proper or useful link for start.

Rupesh Kumar Swami
Software Engineer,
Integrated Solution,
Bikaner (India)

My Company

modified on Thursday, March 6, 2008 10:12 AM

returning value from catch()

rp_suman5-Mar-08 20:41

rp_suman

5-Mar-08 20:41

Is it correct returning value from catch() block?
Can the calling function get return value when there was exception caught by try{}, catch() in called function?

Best Regards,
Suman

Re: returning value from catch()

Roger Stoltz5-Mar-08 21:01

Roger Stoltz

5-Mar-08 21:01

Provided that the function returns a value of that type it is correct in the aspect of C++ syntax to return a value from inside a catch block.

However, I would rather have the return statement outside the catch block since in my opinion the code would be easier to read. I would have a return value at function scope that I would assign a value inside the catch block and return it at the last line of the function.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

How simulate ctrl+alt+delete in vista

vinorathna5-Mar-08 20:24

vinorathna

5-Mar-08 20:24

i want to sent ctrl+alt+delete to remote computer,
i using postmessage() API, its working fine all os except VISTA.
is there any chance to send/simulte ctrl+alt+delete in VISTA.
Anybody hav ideal,plz help me.

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