Pointers [modified] - C / C++ / MFC Discussion Boards

Joe Woodbury23-Jun-06 9:25

23-Jun-06 9:25

The string "File Type" is 9 characters long; you are not writing/reading the null terminator. (Oddly, the compiler should have warned you about an overflowed buffer.)

David's example is good, except I would make type 10 characters. I would also place #pragma pack(1) before the structure and #pragma pack(0)#pragma pack() after.

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

-- modified at 16:36 Friday 23rd June, 2006

Re: Binary File IO

Jumpin' Jeff23-Jun-06 9:50

Jumpin' Jeff

23-Jun-06 9:50

Thanks Joe, but there is no null terminator.
That is the way the file is previously constructed. My example is just a very simple representation of the actual file.

It is X characters, followed by a file major version, then file minor version identifier.

Can you explain what #pragma pack will do for me?

Re: Binary File IO

David Crow23-Jun-06 9:55

David Crow

23-Jun-06 9:55

Jumpin` Jeff wrote:
Can you explain what #pragma pack will do for me?

See here.

"The largest fire starts but with the smallest spark." - David Crow

"Judge not by the eye but by the heart." - Native American Proverb

Re: Binary File IO

Jumpin' Jeff23-Jun-06 9:59

Jumpin' Jeff

23-Jun-06 9:59

Ok, I added the #pragma pack as you suggested, but left the type 9 characters, for when I changed it to 10, I came up with exactly what I did with David's example. The #pragma packs fixed the version data, but not the type. Still reads "File Type@", and I get 3 warnings...

warning C4081: expected 'newline'; found ';'
warning C4086: expected pragma parameter to be '1', '2', '4', '8', or '16'
warning C4081: expected 'newline';

Jeff

Re: Binary File IO

Joe Woodbury23-Jun-06 10:37

Joe Woodbury

23-Jun-06 10:37

My mistake, it should be #pragma pack()

For the compare, try strncmp(struct.string, realString, sizeof(struct.string))

Anyone who thinks he has a better idea of what's good for people than people do is a swine.
- P.J. O'Rourke

Entry Points into Exe files

Hibelton23-Jun-06 8:53

Hibelton

23-Jun-06 8:53

Here we have a simple entry point into a DLL

<br />
AFX_EXT_CLASS bool EntryPoint( void );<br />
<br />
and:<br />
<br />
bool EntryPoint()<br />
{<br />
    return true;<br />
}<br />

Which we can use with AfxLoadLibrary, and GetProcAddress. Yay and hooray! What I need is a way to do that with EXEs. See I need to be able to run some code dynamically based on files in a directory, and it has to work on both DLL's and EXE's. I thought I have read in the past about alternative entry points on EXE's, and you can load an EXE with AfxLoadLibrary, but you can't use GetProcAddress on it.

Re: Entry Points into Exe files

ovidiucucu24-Jun-06 7:22

ovidiucucu

24-Jun-06 7:22

Like form a DLL, you can export a function from an EXE as well.

Ovidiu Cucu
Microsoft MVP - Visual C++

Pointers [modified]

Jay0323-Jun-06 8:16

Jay03

23-Jun-06 8:16

Can someone tell me what is going on in the ObjectRoot constructor and also how the ObjectRootPtr is declared. Is the pointer pointing to a new array called ms_instances of size 21 and assigns a value of NULL to all ms_instance[0], ms_instance[1],.....ms_instance[20].....

PS: WHAT DOES THE SECOND LINE MEAN .... ARE YOU MAKING THE POINTER ObjectRootPtr point to class member ms_instances of size 21. I thought it was something like ObjectRootPtr = new ms_instances;

typedef ObjectRoot* ObjectRootPtr; <br />
static ObjectRootPtr ms_instances[MAX_INSTANCES];<br />
<br />
//! Static variable definition<br />
RTI::RTIambassador*          ObjectRoot::ms_rtiAmb     = NULL;   <br />
RTI::ObjectClassHandle       ObjectRoot::ms_classId    = 0;<br />
const char*                  ObjectRoot::ms_classIdStr = NULL;<br />
<br />
ObjectRootPtr   ObjectRoot::ms_instances[MAX_INSTANCES] =  // MAX_INSTANCES = 21<br />
{ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,<br />
  NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };<br />
unsigned int ObjectRoot::ms_numInstances = 0;<br />
<br />
ObjectRoot::ObjectRoot()<br />
{<br />
 //! Add this new object to the extent (collection) of all instances.<br />
   if (ms_numInstances < MAX_INSTANCES)  // ms_numInstances < 21<br />
      ObjectRoot::ms_instances[ ObjectRoot::ms_numInstances++ ] = this;<br />
}

-- modified at 14:19 Friday 23rd June, 2006

Re: Pointers

Jun Du23-Jun-06 8:52

Jun Du

23-Jun-06 8:52

I'll try to explain line by line.

static ObjectRootPtr ms_instances[MAX_INSTANCES];

Array of static pointers.

//! Static variable definition
RTI::RTIambassador* ObjectRoot::ms_rtiAmb = NULL;
RTI::ObjectClassHandle ObjectRoot::ms_classId = 0;
const char* ObjectRoot::ms_classIdStr = NULL;

Initialization of static and constant static data.

ObjectRootPtr ObjectRoot::ms_instances[MAX_INSTANCES] = // MAX_INSTANCES = 21
{ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };

Initialization of the static pointers defined by the second line above.

Jay03 wrote:
PS: WHAT DOES THE SECOND LINE MEAN .... ARE YOU MAKING THE POINTER ObjectRootPtr point to class member ms_instances of size 21. I thought it was something like ObjectRootPtr = new ms_instances;

No. It defines an array of pointers. No instantiation involved. It's easy to understand if you replace ObjectRootPtr with ObjectRoot*. The first line defines this replacement.

Best,
Jun

Re: Pointers

Jay0323-Jun-06 9:19

Jay03

23-Jun-06 9:19

For the first part..... what do STATIC POINTERS DO?

In the last part. ObjectRootPtr is pointer to an ObjectRoot object. Now this ObjectRootPtr was pointing to ms_instances[21] of size 21. And finally the ms_instances[21] points to NULL

I believe this is what you meant.

The big picture is:

ObjectRootPtr ---> ms_instances[0] --- > NULL
---> ms_instances[1] --- > NULL
---> ms_instances[2] --- > NULL
---> .............. --- > NULL
---> .............. --- > NULL
---> ms_instances[20] --- > NULL

BTW Thanks for your reply JUN Smile | :)

Re: Pointers

Zac Howland23-Jun-06 10:08

Zac Howland

23-Jun-06 10:08

The pointers are not static. The memory allocated to hold the pool of pointers is. Basically, they only want to have 21 instances (maximum) of this object. They created a pool to hold references for all active instances. At startup, those instances are initialized to NULL (since they don't point to anything).

The declaration static ObjectRootPtr ms_instances[21] is declaring a static array of 21 pointers to ObjectRoot objects.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week

Zac

Re: Pointers

Jun Du23-Jun-06 10:30

Jun Du

23-Jun-06 10:30

You're right. It's a static array of pointers, not an array of static pointers. Thanks for pointing this out Rose | [Rose]

Best,
Jun

Re: Pointers

Jun Du23-Jun-06 10:15

Jun Du

23-Jun-06 10:15

Jay03 wrote:
For the first part..... what do STATIC POINTERS DO?

Static is in terms of scope. Like any static variable, a static pointer is shared by all instances of this class, rather than a specific instance. As a matter of fact, it exists before any instance is created. That is why we refer to it as <class_name>::<pointer_name>.

Jay03 wrote:
In the last part. ObjectRootPtr is pointer to an ObjectRoot object.

Correct.

Jay03 wrote:
Now this ObjectRootPtr was pointing to ms_instances[21] of size 21.

Well, a correct interpretation should be "Now you define a (static) array (say, 21) of such pointers (ObjectRootPtr)".

Best,
Jun

accessing an ftp server

LCI23-Jun-06 8:15

LCI

23-Jun-06 8:15

If i have an ftp server such as:
tennis.tournament.com:9662

Is there a way in a web browser to pull up that site and include the user id and password in the string so that this data is not prompted.

So for example:
tennis.tournament.com:9662:username:passwd

I know this is possible but the exact characters in between the user name and passwd i am not sure of.

Thanks,

Re: accessing an ftp server [modified]

LCI23-Jun-06 10:39

LCI

23-Jun-06 10:39

When i use SHellexecute, i am able to to use the user id and password to get to the ftp server. However, i am attempting to play a .avi file that is on that ftp server. If i were to attach the .avi file name like so:

strFtpVideoLocation = "ftp://usr:paswd@lrgftp.monster-ga.com:9662/test.avi";
ShellExecute(AfxGetMainWnd()->m_hWnd,"open",strFtpVideoLocation, NULL, NULL, SW_SHOWNORMAL );

this does not work to play the video

But i can do

strFtpVideoLocation = "ftp://usr:paswd@lrgftp.monster-ga.com:9662/";
ShellExecute(AfxGetMainWnd()->m_hWnd,"open",strFtpVideoLocation, NULL, NULL, SW_SHOWNORMAL );

without the .avi file name and this takes me to the server with all the files and i have to double clip on the clip that i want. I just want to be able to play it and not have a user double click it to play.

-- modified at 16:45 Friday 23rd June, 2006

Trapping the Mouse

Scott P. Chapman23-Jun-06 7:42

Scott P. Chapman

23-Jun-06 7:42

My first post, here. Hope you can help.

Two questions.

1. In a CListCtrl displayed in Report view mode, with a header labeling the columns, I need to trap a mouse right button down message with the cursor in the header. The control has a native function to trap the left mouse button on a click in the header, but neither control nor the dialog are able to see the right mouse button when the header is clicked. It would also be nice to have MFC tell me which column was clicked, but I can do that with a little math on the mouse position and the CHeaderCtrl pointer. (NOTE: I have tried subclassing the CListCtrl CHeaderCtrl member to no avail.)

2. The dialog in question is resizeable. I want to resize and relocate controls on the dialog when it is resized. I can do that in the OnSizing() handler but redraw is very clumsy. I'd rather do it all at once when the resize has stopped. However I can't seem to detect the left mouse button up message from the dialog when the mouse is moving the dialog border. Any way to detect when resizing has finished?

Development is in Visual Studio .Net Professional, 2003 edition

Any suggestions?

Thanks in advance

Scott

Scott P. Chapman
Voss Scientific Inc.
scottc@vosssci.com

Netscape plugin question (C++)

Dennis Gourjii23-Jun-06 7:14

Dennis Gourjii

23-Jun-06 7:14

Dear colleagues,

Does anyone know of a way to create a Netscape plugin (in C++) that would be always active for whatever MIME type is currently loaded?

What I need is to slightly modify the contents of any and all pages opened. Please direct me to where to look for a solution.

The Netscape Plugin SDK documentation gives no answer to this. Is it really impossible to "filter" page content?

Thanks in advance!

two toolBars side by side

LeeeNN23-Jun-06 7:14

LeeeNN

23-Jun-06 7:14

in My MDI, i have two toolBars. when run app, the standard toolBar is on top, another toolBar is below it. How can I manage the second toolBar beside the standard toolBar?

thanks Sniff | :^)

Re: two toolBars side by side [modified]

ovidiucucu24-Jun-06 6:33

ovidiucucu

24-Jun-06 6:33

// NOTE: this is just a draft example to show the idea
class CMainFrame : public CMDIFrameWnd
{
// ...
   CToolBar    m_wndToolBar;
   CToolBar    m_wndToolBar2;
// ...
};

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
// ... create and other blah-blahs ...

   m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);
   EnableDocking(CBRS_ALIGN_ANY);

   DockControlBar(&m_wndToolBar);

   RecalcLayout();
   
   CRect rect;
   m_wndToolBar.GetWindowRect(rect);
   rect.OffsetRect(rect.right, 0);

   m_wndToolBar2.EnableDocking(CBRS_ALIGN_ANY);
   DockControlBar(&m_wndToolBar2, AFX_IDW_DOCKBAR_TOP, rect);

   return 0;
}

Ovidiu Cucu
Microsoft MVP - Visual C++

-- modified at 12:34 Saturday 24th June, 2006

Re: two toolBars side by side

LeeeNN24-Jun-06 13:12

LeeeNN

24-Jun-06 13:12

Thank you very much. I spend lots of time trying to figure it out. Smile | :)

modules

Tara1423-Jun-06 5:55

Tara14

23-Jun-06 5:55

Hi,

Fortitudine Vinsinues!

Re: modules

Jun Du23-Jun-06 5:56

Jun Du

23-Jun-06 5:56

Best,
Jun

Re: modules

Tara1423-Jun-06 6:00

Tara14

23-Jun-06 6:00

Sorry. I don't know what happened. I just pressed the enter key and the message got posted before I could type my question!!

My question:

I have often come across statements such as 'this program has the following modules' or 'the program should have accounting,financing etc modules'.

What exactly are modules? How can one create different modules and then integrate it into the main program in vc++6 using mfc?

Thanks,
Tara

Fortitudine Vinsinues!

Re: modules

Zac Howland23-Jun-06 6:08

Zac Howland

23-Jun-06 6:08

A module is a unit of related code. It is just an organizational term. For example, you may have an accounting module that supports balancing checkbooks, producing income statements, calculating interest and dividends, etc., that is all compiled into a library and used by the main application (which, presumably, would have something to do with accounting). Alternatively, that module could be built as part of the application itself.

The term "module" doesn't convey enough information to tell you how the application is organized, just that it is organized into compartments.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week

Zac

Re: modules

Tara1423-Jun-06 6:18

Tara14

23-Jun-06 6:18

OK.

I am coding a program that has seprate dialog boxes that do something with budget, payroll, piecharts etc. There are no individual libirary made but the dialog boxes have their own classes. So can I call safely call budget, payroll as modules?

Fortitudine Vinsinues!

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