C / C++ / MFC

ifstream - reading same data over and over

11-Jul-07 11:03

a_b_pathak wrote:
I'm not using Set/GetWindowText because i'm using Control Variable

Then you can use the CWnd::GetWindowText/CWnd::SetWindowText methods, as DavidCrow stated.

FYI - You don't always need to use UpdateData()...see Avoiding UpdateData[^]

Mark

Mark Salsbery
Microsoft MVP - Visual C++

This episode brought to you by the number 3

moonraker92811-Jul-07 9:34

moonraker928

11-Jul-07 9:34

Background:
I have two streams, one that writes to a text file called replay.txt, and one that reads from replay.txt. Both events occur while my app is running. So the basic architecture is that while I am simulating something, the app is writing to replay.txt keep track of position of objects and sensors and isDone is false. When the simulation is complete, isDone is true, and the app reads from replay.txt and uses the data in the file to replicate the simulation (like a replay video). dg_replay is the stream that reads from the file. Following the the text file data:

replay.txt
---------
dg_bead
-15
5
5
1
0
dg_grasper
0
0
0
0

Problem: In line marked (A), the values read into x,y,z,d,ts are -15,5,5,1,0 respectively. Then i++ which means that that (i=0) stuff is not going to be processed again. The next process is going to be in the else clause which reads in x,y,z,ss. Now logically, as i would think, the next four numbers should be 0,0,0,0 respectively in those variables. However the data read in to x,y,z,ss is also -15,5,5,1,0!! The same data is read twice..WHY??!

code:
(note #1: i have initialized all variables in the beginning of the file - not shown)
(note #2: this code snippet is part of a function that is called every 1/30th of a second which basically makes this part of a loop)
-----
if (isDone) {
cerr << "eof: " << dg_replay.eof() << "\n";
if (!dg_replay.eof()) {
if (i == 0) { // signals the app to read in the initial states in the file
dg_scenario::dg_video.close();
dg_scenario::video = 1;
if (dg_replay.is_open()) dg_replay.getline(tool_name,256);
(A) dg_replay >> x >> y >> z >> d >> ts;
universe->findObject(tool_name)->CenterObject();
universe->findObject(tool_name)->Translate(x,y,z);
universe->findObject(tool_name)->setDynamicsInt(d);
universe->findObject(tool_name)->being_grabbed = ts;
dg_replay.getline(tool_name,256);
} else {
// process sensor stuff - PROBLEM: reading in the same #s (-15,5,5,) everytime...
(B) dg_replay >> x >> y >> z >> ss;
xyz.x = x; xyz.y = y; xyz.z = z;
left_down = ss; // mouse sensor state - if left_down is 0, then its false and forcep is open etc..
}
i++;
} else {
i = -1;
dg_replay.close();
}
}

--
dg

Mark Salsbery11-Jul-07 10:23

11-Jul-07 10:23

Are you reopening the file every time this is called? If so, you may need to keep track of the
file pointer so you can seek past the last read data each time.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

This episode brought to you by the number 3

moonraker92811-Jul-07 11:00

moonraker928

11-Jul-07 11:00

the file is opened for reading in at the very top of the file where i initialize of the variables in th header class. i am assuming that this happens only once... these are the lines:

code:
--------

extern springCore* springApp;<br />
<br />
extern int window_height, window_width;<br />
extern int wf_window_id;<br />
extern void Reshape(int w, int h);<br />
extern SensorArray sensorarray;<br />
extern int current_sensor_index;<br />
<br />
// counters for playing audio and video files<br />
int loop_1, loop_2, loop_3, i = 0;<br />
<br />
// globals<br />
int dg_scenario::debug = 0;<br />
int dg_scenario::wf = 1;<br />
int dg_scenario::video = 0;<br />
double len = 5.0;<br />
<br />
// mouse sensor button values<br />
extern int left_down, right_down, middle_down;<br />
<br />
// init ofstream and ifstream and their variables<br />
ofstream dg_scenario::dg_video("replay.txt", ios::out); <-- for reading INTO the file<br />
ifstream dg_scenario::dg_replay("replay.txt", ios::in); <-- for reading OUT OF the file<br />
char tool_name_1[256];<br />
char tool_name_2[256];<br />
// store point3Ds, dynamics, tool state, and sensor state<br />
double x,y,z = 0.0;<br />
int d,ts,ss = 0;<br />
Point3D xyz; // new position for the sensor

--
dg

moonraker92811-Jul-07 11:27

moonraker928

11-Jul-07 11:27

OK - i did some playing around and some googling and for some reason if I replace:

dg_replay.getline(tool_name_2,256);

with:

dg_replay >> tool_name_2;

the numbers are read in successfully..

weird..i feel lucky!

--
dg

Mark Salsbery11-Jul-07 11:37

Getting the Tag Property to work for me

11-Jul-07 11:37

Cool

Mark Salsbery
Microsoft MVP - Visual C++

This episode brought to you by the number 3

InOut.NET11-Jul-07 7:53

InOut.NET

11-Jul-07 7:53

I'm sorry for this re-post. I invested much time in my design and need to get it working.

I've got a Wizard Form where i create controls in runtime.

I need to attach the reference/pointer of a String/double variable to a control. This variables exists in another class. so when the Wizard finishes, i iterate through all the controls and each control updates it's own referenced varaible. In .NET i used the Control.Tag property (is of type Object - that was easy). Want to do the same in C++ but the Control->Tag is of int type.

Im missing something. Help me to convert the parameter Value:

<br />
void ExcuteWizard(..., AnsiString &Value)<br />
{<br />
TTextbox ctrl = new ....;<br />
<br />
ctrl->Tag = Value; //<< how do i convert the Value parameter?<br />
<br />
}<br />
void FinnishWizard()<br />
{<br />
for each control{<br />
((&AnsiString)Control->Tag) = Control->Text; //<<and now back to the reference type?<br />
}<br />
}<br />
<br />

Have someone a theory or explanation with regards to pointer and reference conversions? From a Pointer to a Int back to the Pointer. Hope you guys understand what i'm trying to do.

Thanks.

USB device message detector

Beveloper11-Jul-07 7:00

Beveloper

11-Jul-07 7:00

I need a simple Windows application to detect messages from a USB drive. When the application detects that a USB device has been inserted, I need to launch another application.

I have found an example which works in .NET environments but I can't guarantee that all my users will be working on .NET-supported platforms.

Does anyone know of a simple C++ application containing a basic message loop that I can adapt? I don't care about the UI.

Alternately, is there an easy way to convert .NET code so that it will work on a non-.NET platform?

I'm working in Visual C++ 2005 Express.

Thanks!

Re: USB device message detector

ksrameshkanth11-Jul-07 21:59

ksrameshkanth

11-Jul-07 21:59

Hi,
I think you can handle ON_WM_DEVICECHANGE(). Also refer the following link
http://www.codeproject.com/system/HwDetect.asp

Regards,
Rameshkanth

Cut a bitmap under GDI+

Chen-XuNuo11-Jul-07 6:36

Chen-XuNuo

11-Jul-07 6:36

I want to cut a bitmap and save the selection I cut what is anomalistic under GDI+.Is there any program that I can refer to?

Thanks.

Re: Cut a bitmap under GDI+

Mark Salsbery11-Jul-07 9:04

Re: Cut a bitmap under GDI+

11-Jul-07 9:04

Do you mean something like this?

// CropLeft, CropTop, CropWidth, CropHeight are INTs defining the portion of the source image
// to copy to the new destination image
 
Gdiplus::Bitmap SrcBitmap(...);
...
Gdiplus::Bitmap DstBitmap(CropWidth, CropHeight, SrcBitmap.GetPixelFormat()); 
Graphics DstGraphics(&DstBitmap);
DstGraphics.DrawImage(&SrcBitmap, 0, 0, CropLeft, CropTop, CropWidth, CropHeight, UnitPixel);

Mark

Mark Salsbery
Microsoft MVP - Visual C++

This episode brought to you by the number 3

Chen-XuNuo11-Jul-07 19:36

Chen-XuNuo

11-Jul-07 19:36

I am not so familiar with GDI+,so I don't know that the code your provided can wheather achieve my purpose definitely.What I mean is the region in the bitmap is not necessarily a rect,it is mainly region that I draw with mouse.So it is a irregular region.Could you get it?;P

Re: Cut a bitmap under GDI+

Mark Salsbery12-Jul-07 5:08

Help aout paint none-client area

12-Jul-07 5:08

Chen-XuNuo wrote:
What I mean is the region in the bitmap is not necessarily a rect,it is mainly region that I draw with mouse.

You could create a GraphicsPath object from the mouse points defining the outline and then
use Graphics::SetClip() to set the clipping region to the GraphicsPath in the destination
Graphics object before drawing the bitmap.

Mark

Mark Salsbery
Microsoft MVP - Visual C++

This episode brought to you by the number 3

kcynic11-Jul-07 6:22

kcynic

11-Jul-07 6:22

I have a dialog-based program,
I want to draw my own title bar,so I completement ON_WM_NCPAINT() message of the dialog.
In the OnNcPaint() funtion,I wrote:
CDC* pDC=GetWindowDC();
CDC memDC;
BOOL ret=memDC.CreateCompatibleDC(pDC);
int nSaveDC=pDC->SaveDC();
CBitmap bmp;
ret=bmp.LoadBitmap(IDB_LOGIN);//IDB_LOGIN is a bitmap resource ID
memDC.SelectObject(&bmp);
CRect rc;
GetWindowRect(&rc);
ScreenToClient(&rc);
ret=pDC->BitBlt(0,0,rc.Width(),m_captionRect.Height(),&memDC,0,0,SRCCOPY);
bmp.DeleteObject();
ReleaseDC(&memDC);

pDC->RestoreDC(nSaveDC);

the code works well when the dialog was shown first time,but when the dialog should be redrawn,the title bar went back to its default look(the blue bar).
Someone would like to tell me why?And how to resolve it?
Thanks.

GOOD LUCK.

DevMentor.org12-Jul-07 12:01

DevMentor.org

12-Jul-07 12:01

i am not sure but it sounds like you need to send an update to your non-client area Big Grin | :-D

Yours Truly, The One and Only!

kcynic13-Jul-07 1:00

kcynic

13-Jul-07 1:00

Thanks.
Now,it works well.But if you would like to tell me how to make the client area's left-bottom and right bottom is round conor?

DevMentor.org13-Jul-07 12:10

DevMentor.org

13-Jul-07 12:10

i'm afraid i have not done GDI and custom drawing in a sometime Smile | :)

these days most of my development is focued on non-gui core development!

i am sure you should be able to find custom driawing how-to on this site understand mfc section, have you tryed that?

Yours Truly, The One and Only!

kcynic13-Jul-07 12:26

kcynic

13-Jul-07 12:26

Thanks,but I has searched in this site faild.

GOOD LUCK.

DevMentor.org13-Jul-07 20:46

DevMentor.org

13-Jul-07 20:46

ok here's how to do it if you're resourceful.

the first time around before you window come up you will have to grab the background and draw it into a z-buffer(off-screen buffer), only grab the rectangle area of the bottom portion you will need the round corned, follow me, then you do your non-client magic drawing in the bottom portion of your window!

that is the first step, the 2nd step once you get this working it to make it be able to grab area while your window is getting move around...remember to paint back the original screen background if that is required, most likely you will not have to worry about this last part.

hope that helps! remember just use the window DC and you will need to covert the between screen point and client point!

hope that help....learn to do this for yourself, you will be a better developer for it Poke tongue | ;-P

Yours Truly, The One and Only!

Convert Int to Byte

simoncoul11-Jul-07 6:19

simoncoul

11-Jul-07 6:19

I'm trying to convert and short int into 2 bytes to be send through an ethernet comm. This is what I'm trying to do:

    char calcsendbuf[3];
short int data;
printf("Please Enter The Data:");
scanf("%d", &data);
calcsendbuf[0] = char(data % 256);
calcsendbuf[1] = char(floor(double(data/256)));
printf("byte 0: %u\n", calcsendbuf[0]);
printf("byte 1: %u\n", calcsendbuf[1]);

I input 32767 as the data and it should be printing 255 and 127, but I'm getting 4294967295 and 127. Any ideas of what is going wrong here, or maybe a different way of doing things?

Thanks

David Crow11-Jul-07 7:21

David Crow

11-Jul-07 7:21

simoncoul wrote:
I input 32767 as the data and it should be printing 255...

Since a char has a range of -128 to 127, trying to assign it a value of 255 will not do what you want.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Cyrilix11-Jul-07 7:21

Cyrilix

11-Jul-07 7:21

You will never get 255 with a signed char, since chars are only 1 byte (your range is 2^7 both ways). Use the unsigned char instead.

simoncoul11-Jul-07 7:52

simoncoul

11-Jul-07 7:52

Ok using the unsigned char worked for the display but the send function in winsocks asks for a char *, how do I go about getting sending a single byte of 255 through ethernet using winsocks.