C / C++ / MFC

STL list member function(S)

20-Nov-15 3:03

OP deleted his question; I can guess why.

Amr.Mohammad8719-Nov-15 7:05

Re: STL list member function(S)

19-Nov-15 7:05

void assign(size_type n, el const T& el = T())

This function is a member function of the STL list class and I do not understand the bolded part. I understand the const T& el is a reference to a constant parameter which means I cannot change the value/content of the passed argument + I understand that el = T() means a default parameter so if there is no argument passed in the calling function the el will use the no-argument constructor of the T() type OK. But what make me confused the el at the beginning before the const?!!! so if someone can fill the blank gaps for me I will be grateful Smile | :)

. Thanks in advance.

C^hris L^osinger19-Nov-15 7:41

C^hris L^osinger

19-Nov-15 7:41

which compiler are you using?

i haven't been able to find any std::list::assign definitions that look like that.

http://www.cplusplus.com/reference/list/list/assign/[^], for both C++98 and C++11, has

C++

void assign (size_type n, const value_type& val);

MSVC 8.0 has the same. so does the current MSDN (https://msdn.microsoft.com/en-us/library/w3eba3dd.aspx?f=255&MSPPError=-2147217396[^])

image processing toolkits | batch image processing

Re: STL list member function(S)

Amr.Mohammad8719-Nov-15 12:47

Re: STL list member function(S)

19-Nov-15 12:47

I read it in a book called "Data Structures and Algorithms in C++, 4th Edition by Adam Drozdek" it was in chapter 3 "Linked Lists" at the beginning of page 110 Smile | :)

. It made me had the feeling of this WTF | :WTF:

when read it, and after searching and find nothing I become like this Poke tongue | ;-P

;P;P (i.e., psycho). Thanks by the way for reply Smile | :)

CPallini19-Nov-15 21:26

CPallini

19-Nov-15 21:26

Looks like a typo, to me.

Returning CBitmap* pointer

_Flaviu18-Nov-15 20:15

_Flaviu

18-Nov-15 20:15

I have wrote a method that load and rescale a CBitmap:

C++

CBitmap* CMyDlg::LoadPicture(CString strFile)
{
	int m_nPictureSize = 170;
	CBitmap* pBitmap = NULL;
	HBITMAP hBitmap = (HBITMAP)::LoadImage(NULL, strFile, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
	if(NULL != hBitmap)
	{
		CBitmap Bitmap, MemBitmap;
		Bitmap.Attach((HBITMAP)hBitmap);
		// rescale CBItmap ....
		// retrieve the final bitmap
		CBitmap* pFinalBitmap = MemDC.SelectObject(pOldBitmap);
		SourceDC.SelectObject(pOldBmp);
		pBitmap = new CBitmap;
		pBitmap->Attach((HBITMAP)pFinalBitmap->GetSafeHandle());
BITMAP bm3;
pBitmap->GetBitmap(&bm3);
TRACE("Width and height INSIDE if condition: %d|%d\n", bm3.bmWidth, bm3.bmHeight);
	}
BITMAP bm4;
pBitmap->GetBitmap(&bm4);
TRACE("Width and height OUTSIDE if condition: %d|%d\n", bm4.bmWidth, bm4.bmHeight);
	return pBitmap;
}

I want to use this method in order to add this created CBitmap pointer to add them into CTypedCBitmapList:

C++

CBitmap* pImage = LoadPicture(strPath);
if(NULL == pImage->GetSafeHandle())
    return 0;
m_PtrArrayBitmap.Add(pImage);

Ok, but the strange thing is that pBitmap from inside of LoadPicture method has correct size inside of 'if' condition, and wrong size outside of 'if' condition:

C++

Width and height INSIDE if condition: 170|170
Width and height OUTSIDE if condition: -858993460|-858993460

Why ? It is not the same pBitmap object ? Could you help me ? Kindly thank for any further help !

Re: Returning CBitmap* pointer

Richard MacCutchan18-Nov-15 21:40

Re: Returning CBitmap* pointer

18-Nov-15 21:40

It appears that the bitmap you are pointing to is a temporary object whose scope is only within the if block. In the following block of code where do pOldBitmap and pOldBmp come from?

C++

CBitmap* pFinalBitmap = MemDC.SelectObject(pOldBitmap);
SourceDC.SelectObject(pOldBmp);
pBitmap = new CBitmap;
pBitmap->Attach((HBITMAP)pFinalBitmap->GetSafeHandle());

_Flaviu19-Nov-15 0:20

_Flaviu

19-Nov-15 0:20

I think I figure out why it doesn't work ... pOldBitmap and pOldBmp are decalred inside of 'if' statement:

C++

	if(NULL != hBitmap)
	{
		//// ......
		// select memory bitmap into memory dc
		CBitmap* pOldBitmap = MemDC.SelectObject(&MemBitmap);
		// create a source dc
		CDC SourceDC;
		SourceDC.CreateCompatibleDC(&cdc);
		// select into source dc the source bitmap
		CBitmap* pOldBmp = SourceDC.SelectObject(&Bitmap);
		//// ......
		// retrieve the final bitmap
		CBitmap* pFinalBitmap = MemDC.SelectObject(pOldBitmap);
		SourceDC.SelectObject(pOldBmp);
		pBitmap = new CBitmap;
		pBitmap->Attach((HBITMAP)pFinalBitmap->GetSafeHandle());
BITMAP bm3;
pBitmap->GetBitmap(&bm3);
TRACE("Width and height INSIDE if condition: %d|%d\n", bm3.bmWidth, bm3.bmHeight);
	}
BITMAP bm4;
pBitmap->GetBitmap(&bm4);
TRACE("Width and height OUTSIDE if condition: %d|%d\n", bm4.bmWidth, bm4.bmHeight);
	return pBitmap;

Re: Returning CBitmap* pointer

Richard MacCutchan19-Nov-15 1:43

19-Nov-15 1:43

Well, that is quite different from the code in your original question.

C++

Member 1215089418-Nov-15 11:38

Member 12150894

18-Nov-15 11:38

If a, b and c are variable of type int. without changing the types write a program to display
C = 1.5 if a is 3 and b is 2

Richard Andrew x6418-Nov-15 12:00

Richard Andrew x64

18-Nov-15 12:00

We don't do your homework. Thumbs Down | :thumbsdown:

The difficult we do right away...
...the impossible takes slightly longer.

Member 1215089418-Nov-15 12:06

Member 12150894

18-Nov-15 12:06

sorry...didnt mean to be rude its just a test i saw somewhere and i dont know how to do it...all i want is for you guys to tell me what its under or explain what im supposed to do not to write the program. I'm a beginner in C++...Pls guys

CPallini18-Nov-15 21:52

CPallini

18-Nov-15 21:52

#include <stdio.h>
int main()
{
  int a,b,c;
  if (a==3 && b==2) printf("C=1.5\n");
  return 0;
}

Jochen Arndt18-Nov-15 22:54

Jochen Arndt

18-Nov-15 22:54

For a precision of one-tenth:

C++

printf("C = %d.%d\n", a / b, abs(((10 * a) / b) % 10));

Change printed background color, how?

«_Superman_»29-Nov-15 19:08

«_Superman_»

29-Nov-15 19:08

I guess the question is hinting type casting[^].

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++) (October 2009 - September 2013)

Polymorphism in C

Tom Stokes17-Nov-15 14:53

Tom Stokes

17-Nov-15 14:53

I use FillRect(...) for the screen but I can't get it to work for a printer. App is pretty much ordinary MFC with Doc/View arch. A little unusual is that I use worker threads for printing and painting. The threads use GDI resources instead of CDC.

Did I hear you ask why? I use an image printer to print straight to jpg files. I want a dark background in some of the jpgs. Then I use Windows Movie Maker to add the jpgs and a soundtrack. Walla, out pops an MP4. Loads of fun.

Re: Change printed background color, how?

Richard MacCutchan17-Nov-15 21:54

Re: Change printed background color, how?

17-Nov-15 21:54

If you use a proper device context it should work just the same: WYSIWYG.

Tom Stokes18-Nov-15 13:48

Tom Stokes

18-Nov-15 13:48

I figured it out, Richard. You have to do a FillRect(...) on the pristine CRect rcl = pInfo->m_rectDraw (in OnPrint()). That should happen before the printer thread is started.

Thanks.

help creating a COM/ATL wrapper for a USB Scanner for VB6

E Wolf16-Nov-15 6:00

E Wolf

16-Nov-15 6:00

My first program in VC6 (ever) is a wrapper so the the DLLs provided by our Scanner vendor can be used in our VB6 application. (They won't provide compatible DLLs)

I did some experimental programs and successfully wrapped the librarys in a vc6 program and created a test dialog to access the function. Good to go.

Then I followed this COM/ATL example:
http://www.codeproject.com/Articles/96/Beginner-s-Tutorial-COM-ATL-Simple-Project

I Created a COM project just like the example, added my includes for the provided vendor DLLs and abstracted access to the library calls.

Wonderfully, magically the library shows up the the VB6 reference list. I include it just like in the example program and when I try to access the simplest function (Is the scanner connected?) the call to the function CRASHES VB6 with an access violation!

I'm at the end of ideas here. I did run depends.exe against the 4 library DLLs that our vendor provided and there are a number of DLL dependencies missing on my machine. Could my problem be those missing dependencies alone? (They reference IE dlls that I don't believe are applicable to anything I'm asking the library to do.)

Thanks for your time.

Re: help creating a COM/ATL wrapper for a USB Scanner for VB6

Richard MacCutchan16-Nov-15 7:25

Capture Screen whenever the display is updated

16-Nov-15 7:25

Quite possibly yes, but it is impossible to be sure. You would need to collect some decent debug information in order to be certain why the crash occurs.

Vijjuuu.16-Nov-15 0:17

Vijjuuu.

16-Nov-15 0:17

hi all,
i am planning to implement a tool which can capture screen only when there is display event from Operating system (for e.g window 7) level. i have idea how to capture a screen at regular interval of time but that's not what i am planning to implement.

the idea is tool will run be running in the background and it must capture the screen only when the screen is updated. i have no idea where to start. i am open for technology (c++ or c# or any other technology)
i request to give me some suggestions/ideas what could be better start.

Thanks
Vijay.

Re: Capture Screen whenever the display is updated

John Torjo16-Nov-15 0:39

John Torjo

16-Nov-15 0:39

Vijjuuu. wrote:
(c++ or c# or any other technology)

0. those are not technologies, they are languages.

1.Capturing the screen is easy
http://blogs.msdn.com/b/dsui_team/archive/2013/03/25/ways-to-capture-the-screen.aspx[^]
http://stackoverflow.com/questions/5069104/fastest-method-of-screen-capturing[^]
There are other ways, just google for "win32 api capture screen"

2. when screen is updated - this is pretty much close to impossible to find out - at least I don't know of a way to do it. The way you can do it is to simply have a timer, capture when the timer is triggered - and if you wish, compare with former screen (bitmap).

3. I'm not sure what you're trying to achieve, since there may be other ways to find out "when screen is updated" depending on your actual needs - perhaps you might be only interested in a specific window(s)? It would be a smart choice to minimize the area you're capturing, since that can indeed take a while and it's not really a good idea to to it too fast (not to mention - what if the user has a few monitors, and/or high resolution ones)

4. If you're just trying to learn programming, I suggest you take an easier task.

Best,
John

-- LogWizard Meet the Log Viewer that makes monitoring log files a joy!

A Data Structures Book Needed

Amr.Mohammad8715-Nov-15 14:14

Re: A Data Structures Book Needed

15-Nov-15 14:14

Greetings,

I am looking for this book 'Data Structures Through C in Depth by S. K. Srivastava, Deepali Srivastava' as a soft copy and I cannot find it if anyone have it as a soft copy if he can upload it for me I will be too much grateful for him. Best regards!.

David Crow16-Nov-15 2:45

David Crow

16-Nov-15 2:45

Have you tried here?

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles

Re: A Data Structures Book Needed

Amr.Mohammad8719-Nov-15 6:56