pointers to functions - C / C++ / MFC Discussion Boards

Member 230136023-Oct-05 10:56

23-Oct-05 10:56

Hello,
I would like that users be able to launch my application from the Shell "Open with" menu.
Can somebody explain how to achieve that?

Thanks

Re: Handling shell command line

David Crow24-Oct-05 3:43

David Crow

24-Oct-05 3:43

See here.

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: Handling shell command line

Allad24-Oct-05 6:51

Allad

24-Oct-05 6:51

Hello,
Thank you for replying. I followed your link.
But I've already call EnableShellOpen in the CWinApp::InitInstance. And my application is listed under "Open with" menu.
When I open a file with the "Open with" menu, the shell actually launch my app. However I don't know how to do further processing like retrieving the file being launched and open it.
Can you help me doing that?

Re: Handling shell command line

David Crow24-Oct-05 7:07

David Crow

24-Oct-05 7:07

Allad wrote:
However I don't know how to do further processing like retrieving the file being launched and open it.

I'm assuming you have either an SDI or MDI application. Yes? If clicking on a particular file opened your application, then the file is already opened and its name can be obtained from the document's GetPathName() method.

"Take only what you need and leave the land as you found it." - Native American Proverb

Re: Handling shell command line

Allad26-Oct-05 9:04

Allad

26-Oct-05 9:04

Thank's. It works.

Re: Handling shell command line

Allad24-Oct-05 6:51

Allad

24-Oct-05 6:51

Re: Handling shell command line

Allad24-Oct-05 6:51

Allad

24-Oct-05 6:51

pointers to functions

Mohammad A Gdeisat23-Oct-05 10:52

Mohammad A Gdeisat

23-Oct-05 10:52

Hi all,

I need to know that when i create a function, say:

int add(int,int);

then I create a pointer to that function:
int(*fp)(int,int); //I think this is the syntax...

the big question is that:

since this pointer points to data in memory, can I copy these data (the actual function code in memory) and copy it to a new location in memory?

I want to have to copies of the function in memory, and use them both.

if I can, how can I deteremine the length(in bytes) of that function? what are the explicit steps do I need to do?????????

Thanx all,
Mohammad Gdeisat

And ever has it been that love knows not its own depth until the hour of separation

Re: pointers to functions

C^hris L^osinger23-Oct-05 14:53

C^hris L^osinger

23-Oct-05 14:53

Mohammad A Gdeisat wrote:
can I copy these data (the actual function code in memory) and copy it to a new location in memory?

no. for one thing, the OS distinguishes between code and data, and vice versa. it takes some serious trickery to execute the stuff your app thinks is data.

Cleek | Image Toolkits | Thumbnail maker

Re: pointers to functions

Mohammad A Gdeisat24-Oct-05 7:09

Mohammad A Gdeisat

24-Oct-05 7:09

Yesterday, when I was playing with Visual C++, I wrote this piece of code:

<br />
#include "iostream.h"<br />
#include "memory.h"<br />
int add(int a, int b)<br />
{<br />
	return a+b;<br />
}<br />
<br />
void main()<br />
{<br />
	typedef int (*func)(int,int);<br />
	func fp;<br />
	fp=add;<br />
<br />
	//allocate memory for the function<br />
	unsigned char *buffer=new unsigned char[100];<br />
	//copy instructions to new location<br />
	memcpy(buffer,fp,97);<br />
<br />
	//make the buffer a pointer to a function<br />
	func fp2;<br />
	fp2=(func)buffer;<br />
<br />
	//cout<<fp(5,6)<<endl;<br />
<br />
	//use the new function to calculate 5+6<br />
	cout<<fp2(5,6)<<endl;<br />
<br />
	//display function data<br />
	cout<<"Function data: \n";<br />
	<br />
	for (int a=0;a<97/4+1;a++)<br />
	{<br />
		cout<<hex<<((int*)buffer)[a]<<endl;<br />
	}<br />
	delete []buffer;<br />
}

I figured out the size of the "function instructions" by trial and error, it was 97 bytes.

After copying function data to a new location in memory and creating a pointer to function that points to the copied function in memory, it just executed normally and smoothly. I was amazed, really!!!

But till now, I have the problem of determining the size of the function data, and everythink will work fine for me....

Can you help me in this??? or anyone else.

Thank you all.....

And ever has it been that love knows not its own depth until the hour of separation

Combo Box, SetCurSel ( 0 )

kevincwong23-Oct-05 10:01

kevincwong

23-Oct-05 10:01

Hi,

I created a dialog with a combo box.
I entered a few items ("A;B;C;D") to
the combox box's property->data field.

I know I need to call SetCurSel ( ) function to
sets the combo box's current selection by
a data index. Otherwise, the combo box appers
empty until I drop the list down.

I also read something about fixing the
problem in OnInitDialog ( ).

But I could not find out how they come together.

I think my question is where is "OnInitDialog".

Should I derive a new class from that combo box?
If that is the case, how my dialog display the
same combo box again?

Any suggestions would be appreciated?

Thanks,

Kevin

Re: Combo Box, SetCurSel ( 0 )

Graham Bradshaw23-Oct-05 10:22

Graham Bradshaw

23-Oct-05 10:22

OnInitDialog is called by the framework before the dialog is displayed. It's an ideal place to do the sort of thing you want to do (fill combo boxes, set text in text boxes etc). It's a member function of CDialog, so (assuming you're using MFC), you'll need to override this function and put your code in there.

Note that although you are ultimately handling a WM_INITDIALOG message, in this case you don't need an entry in the message map, just an override of the base class function.

Re: Combo Box, SetCurSel ( 0 )

Mohammad A Gdeisat23-Oct-05 10:43

Mohammad A Gdeisat

23-Oct-05 10:43

Hi-

go to class wizard and select the dialog box class on which your combo box is in, then from create an event handler(also from class wizard) for the WM_INITDIALOG message or the OnInitDialog() function, place your code to initialize (select the item you want in a combo box), the code in this function will be executed when your dialog box is initialized, and before it is visible on the screen.

Regrds,
Mohammad Gdeisat

And ever has it been that love knows not its own depth until the hour of separation

Re: Combo Box, SetCurSel ( 0 )

kevincwong23-Oct-05 21:14

kevincwong

23-Oct-05 21:14

Great, it works.

One more question.

I have about 15 data (a;b;c;d;e;...) with my combo box.
When I clicked the combo box, it only showed one entry
at a time when I hit the up or down arrow.

How can I show multiple rows to be selected?

Thanks,

Kevin

Re: Combo Box, SetCurSel ( 0 )

S Douglas24-Oct-05 0:17

S Douglas

24-Oct-05 0:17

kevincwong wrote:
How can I show multiple rows

If you want the combo box to display more than on item when clicked, try this

In design mode,
Right click on the drop down box,
Use the selection box to resize the height.

DEBUGGING : Removing the needles from the haystack.

Re: Combo Box, SetCurSel ( 0 )

kevincwong24-Oct-05 6:07

kevincwong

24-Oct-05 6:07

I got it. It works.

Thank you so much!

Kevin

Re: Combo Box, SetCurSel ( 0 )

S Douglas24-Oct-05 12:24

S Douglas

24-Oct-05 12:24

kevincwong wrote:
Thank you so much!

No problem...

DEBUGGING : Removing the needles from the haystack.

CListCtrl hook error

Member 230136023-Oct-05 6:45

Member 2301360

23-Oct-05 6:45

Hello,
I am using a list control in my MFC Application.
I need to add items to the list control. So I use CListCtrl::InsertItem member method. And my app compile without any problem.
But at runtime, after adding 17 items to the control, the programm ends with a MessageBox displaying "Invalid Hook Descriptor". I've tried several times and it always ends after the 17th item added.
I don't use any hook in my app.I don't even know what a hook is.
Can somebody helps me? Frown | :(

Thanks

Re: CListCtrl hook error

steven_wsy23-Oct-05 23:38

steven_wsy

23-Oct-05 23:38

i think your code had some bugs, so you must attach your code.

c++

CTreeView Form

Gamil Mohamad23-Oct-05 4:21

Gamil Mohamad

23-Oct-05 4:21

I Creat an SDI Application with CTreeView as a main view, How can i access and manpulate the CTreeView from a CDialog class in the same application ?

M. Gamal

Re: CTreeView Form

Member 230136023-Oct-05 6:51

Member 2301360

23-Oct-05 6:51

One solution :
- Add a pointer to your main view in the App class
- Then in the CTreeView constructor you initialize the pointer with the local this pointer. You can access the pointer member variable using "theApp" object. It is the current instance of your application and it is availabe since you include your app header (for instance "myApp.h")
-You can access that pointer member everywhere provided that you include the header("myApp.h")

Re: CTreeView Form

Mohammad A Gdeisat23-Oct-05 10:46

Mohammad A Gdeisat

23-Oct-05 10:46

may be you need to pass the handle of the tree view window to the dialog box you create, either by sending a message or a member function call. In your dialog use the handle of the tree view to get a pointer to the tree view, and access it freely

good luck,
Mohammad Gdeisat

And ever has it been that love knows not its own depth until the hour of separation

16 Byte alignment support

Remco Hoogenboezem23-Oct-05 4:15

Remco Hoogenboezem

23-Oct-05 4:15

I would like to align some static variables (floats) to 16 byte boundary's so I can use SSE instructions to speed up calculations. In microsoft visual C++ this is very simple:

__declspec(align(16)) float A[65536];

&A[0]=0x???????0

But for my current project I have to use Borland C++ compiler. The Borland compiler does not support the align keyword. It is very easy to align dynamic variables to 16 byte boundary's using the function VirtualAlloc:

lpAddress=VirtualAlloc(NULL,65536*4,MEM_COMMIT,PAGE_READWRITE);

lpAddress=0x????0000

But if it is possible I would like to use static variables. I have tryed the following:

typedef struct
{
CHAR cPadding[16];

}PADDING;

#pragma pack(16)

PADDING padding;

FLOAT A[65536];

#pragma pack()

#pragma pack(16)

LONG DOUBLE padding1;

LONG padding2;

SHORT padding3;

FLOAT A[65536];

#pragma pack()

but this does not work. Does anyone have experience with this?? Thank You in advance Smile | :)

CGridCtrl Resizing Columns

markdanielmaltby23-Oct-05 3:00

markdanielmaltby

23-Oct-05 3:00

Is it possible to turn off and on resize for individual columns?

Problems with DirectX 8 SDK

dudeua23-Oct-05 1:20

dudeua

23-Oct-05 1:20

I'm writing a project using DirectX 8 SDK in VS 6.

I'm having a problem with following:
Compiler doesn't understand new data types that I need to use.
IDirectSound m_pSound; // OK
IDirectSound8 m_pSound8; //Use of undefined struct IDirectSound8

In dsound.h IDirectSound8 for example defined as new data type only if DIRECTSOUND_VERSION constant is more than 0x8000.

I tryed to define it as 0x8000 in my stdafx.h, but it didn't help.

How do I force my copmiler to understand new data types?

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.