Re: typedef Handle - C / C++ / MFC Discussion Boards

Jay0329-Jun-06 4:40

29-Jun-06 4:40

Yeah it is actually used in RTI to call upon different federates
Im not sure if u are familiar with RTI.
What it does is, interacts with multiple simulations which the simulations interacting with each other. Its more like a third party.

Re: typedef Handle

Jun Du29-Jun-06 5:14

Jun Du

29-Jun-06 5:14

A little bit, but I haven't done anything seriously yet. I don't like SOM/FOM stuff.

Are you developing a HLA federation now? It's quite a lot of effort from my understanding. Which vender's RTI are you using, VTC, MAK, PITCH, etc?

Best,
Jun

Re: typedef Handle [modified]

Viorel.29-Jun-06 4:34

Viorel.

29-Jun-06 4:34

Some of us use it in very rare situations like this:

struct Handle
{
   // . . .
};

struct Handle2
{
    typedef Handle ****Handle;
    // . . .
};

-- modified at 10:41 Thursday 29th June, 2006

It means that within Handle2, Handle will be a pointer to a pointer to a pointer to a pointer which points to a value of first structure.

Re: typedef Handle

Jay0329-Jun-06 4:40

Jay03

29-Jun-06 4:40

Why is handle used?

Re: typedef Handle

Viorel.29-Jun-06 4:48

Viorel.

29-Jun-06 4:48

Probably Handle name is used for some convenience, or maybe to hide the original meaning of Handle.

Re: typedef Handle

ovidiucucu29-Jun-06 4:59

ovidiucucu

29-Jun-06 4:59

Yeah, that's correct. However, I'm wondering:

where need so many levels of indirection?
wouldn't be better to change anyhow the defined type name to be clearer for anybody what's there?

Ovidiu

Re: typedef Handle

Viorel.29-Jun-06 5:15

Viorel.

29-Jun-06 5:15

I think we should ask the authors of RTI, where such weird constructions are used, according to Jay03 message.

Re: typedef Handle

Zac Howland29-Jun-06 4:45

Zac Howland

29-Jun-06 4:45

It is a very poor way to declare a new type. The reason it is poor is because of the naming. The goal it is trying to accomplish is to declare a new type that is a pointer-to-a-pointer-to-a-pointer-to-a-pointer-to-a-Handle. A better way to write it would be either of the following:

Option 1:
typedef RedirectedHandle ****Handle;

Option 2:

// assuming Handle is in global namespace
namespace MyStuff
{
    typedef Handle **** ::Handle;
}

An even better solution would be to not use that many levels of indirection (who needs 4 levels of indirection for a Handle?) and to use smart pointers.

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: typedef Handle

ovidiucucu29-Jun-06 5:04

ovidiucucu

29-Jun-06 5:04

A little bit better for everybody... :thumb:

Ovidiu

about button OwnerDraw [modified]

HOW WHAT29-Jun-06 3:54

HOW WHAT

29-Jun-06 3:54

void CMyButton::PreSubclassWindow()
{
UINT nBS;

nBS = GetButtonStyle(); // GetStyle & 0xFF == all bs_* OR operator ?

m_nTypeStyle = nBS & BS_TYPEMASK; // GetStyle & 0xFF & 0xF ==? == all bs_* OR operator ?

if (nBS & BS_CHECKBOX)
m_bIsCheckBox = TRUE;

if (m_nTypeStyle == BS_DEFPUSHBUTTON) // why not use m_nTypeStyle & BS_DEFPUSHBUTTON
{
m_bIsDefault = TRUE;
}

ASSERT(m_nTypeStyle != BS_OWNERDRAW);// why not use !(m_nTypeStyle & BS_OWNERDRAW)

ModifyStyle(BS_TYPEMASK, BS_OWNERDRAW, SWP_FRAMECHANGED);

CButton::PreSubclassWindow();
}

LRESULT CMyButton::OnSetStyle(WPARAM wParam, LPARAM lParam)
{
UINT nNewType = (UINT)(wParam & BS_TYPEMASK); // why not use GetButtonStyle() & BS_TYPEMASK -> wParam & 0xFF & 0xF?

if (nNewType == BS_PUSHBUTTON) // why not use nNewType & BS_PUSHBUTTON? (if SetButtonStyle(BS_OWNERDRAW | BS_PUSHBUTTON)
{
m_bIsDefault = FALSE;
}

return DefWindowProc(BM_SETSTYLE,
(wParam & ~BS_TYPEMASK) | BS_OWNERDRAW, lParam); // why in here remove BS_TYPEMASK style?
}

thanks.

Re: about button OwnerDraw

Sarath C29-Jun-06 3:58

Sarath C

29-Jun-06 3:58

what we have to do with this?

SaRath.

"It is your attitude, not your aptitude, that determines your altitude - Zig Ziglar."
My Blog | Understanding State Pattern in C++

Re: about button OwnerDraw

ovidiucucu29-Jun-06 4:13

ovidiucucu

29-Jun-06 4:13

Let me guess!
It's the last Code Inspection Report for your project. Right? Smile | :)

Ovidiu Cucu
Microsoft MVP - Visual C++

Re: about button OwnerDraw

HOW WHAT29-Jun-06 4:56

HOW WHAT

29-Jun-06 4:56

this is a class from codeproject, now its class name is CButtonST(version 3.5 is CMyButton).

I only want to know why did author write that otherwise then me?

Problems including previously done class

RedSpyder29-Jun-06 3:03

RedSpyder

29-Jun-06 3:03

hi! My name is JC im from Puerto Rico. Right now my C++ knowledge is a bit "limited"
and Im developing an application tthat will end up updating a txt file in an FTP. I found a class that got the perfecy functions i need made by otom and found here
( http://www.codeproject.com/internet/ftpclientclass.asp ). The functions I need are exactluy the same he puts as an example:

nsFTP::CFTPClient ftpClient;
nsFTP::CLogonInfo logonInfo("localhost", 21, "anonymous",
"anonymous@user.com");

// connect to server
ftpClient.Login(logonInfo);

// do file operations
ftpClient.DownloadFile("/pub/test.txt", "c:\\temp\\test.txt");

ftpClient.UploadFile("c:\\temp\\test.txt", "/upload/test.txt");

// disconnect
ftpClient.Logout();

dat is basically all i need BUT his work is very hard to understand for me and i just dont know WHAT to include and where to include.. Id appreciate any help you guys can give me. Thanks in advance

-JC

Re: Problems including previously done class

Jun Du29-Jun-06 3:26

Jun Du

29-Jun-06 3:26

I think he/she still maintains that article page. Why don't you post a message there. I am sure he/she will be happy to assist you.

Best,
Jun

How to write content of file in to a structure

birajendu29-Jun-06 2:55

birajendu

29-Jun-06 2:55

Hi..

I have a charecter file in my hard drive...i want to read the file charecter by charecter and i wat to write those charecters to a stucture irrespective of their member variables...

birajendu
CyberG India
Delhi
India

Re: How to write content of file in to a structure

Cedric Moonen29-Jun-06 2:58

Cedric Moonen

29-Jun-06 2:58

You can still use the fread function and pass the address of your structure. But you have to take care of that because pading bytes are added between the members of your structure (so it is quite dangerous to handle that this way).

BTW, why do you want to do such a thing ?

Cédric Moonen
Software developer

Charting control

Re: How to write content of file in to a structure

birajendu29-Jun-06 3:46

birajendu

29-Jun-06 3:46

is there any similar procedure as packed structure

birajendu
CyberG India
Delhi
India

Re: How to write content of file in to a structure

Cedric Moonen29-Jun-06 3:48

Cedric Moonen

29-Jun-06 3:48

birajendu wrote:
is there any similar procedure as packed structure

Uh ? Could you be more explicit ?

Cédric Moonen
Software developer

Charting control

Re: How to write content of file in to a structure

birajendu29-Jun-06 3:55

birajendu

29-Jun-06 3:55

if we use packed structure in c thne there is no byte padding...can we such technique in VC++

birajendu
CyberG India
Delhi
India

Re: How to write content of file in to a structure

Cedric Moonen29-Jun-06 3:58

Cedric Moonen

29-Jun-06 3:58

Yes, you can use pragma pack directive for that. Look at the bottom of this page[^] for an example

But you still didn't answer my question: what is the purpose of doing that this way ?

Cédric Moonen
Software developer

Charting control

Re:

birajendu29-Jun-06 3:56

birajendu

29-Jun-06 3:56

if we use packed structure in c thne there is no byte padding...can we such technique in VC++

birajendu
CyberG India
Delhi
India

Re: How to write content of file in to a structure

Jun Du29-Jun-06 3:49

Jun Du

29-Jun-06 3:49

Two approaches often used:

1) open the file and read the entire content into a buffer.

2) create a file-mapping and map the file content to your memory buffer.

Don't load the file content to a sturcture directly. Load it to a buffer (string) first and then do whatever you like with it.

Best,
Jun

Memory leak [modified]

pierre_ribery29-Jun-06 2:48

pierre_ribery

29-Jun-06 2:48

Hi Gurus!

I have an MFC activeX component which creates a memory leak in the application that uses it. The leak is when exiting program. I have created a small example to show you what happens.

In my activeX component I have this method;

Code:

LONG CThursdayActiveXCtrl::getSomething(VARIANT* pVar)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());

// A safe array of float
CComSafeArray <float> saVars;

// Insert elements into the CComSafeArray
saVars.Add(1); //THIS LINE GIVES A LEAK!!! SEE BELOW
saVars.Add(32);
saVars.Add(43);

// A CComVariant to return to the client
CComVariant varReturn (saVars.Detach ());
varReturn.vt=VT_R4;

return varReturn.Detach (pVar);
}

I have added my activex control to a dialog based MFC application. I have a button, when that button is pushed this method is called:

Code:

void Ctest1Dlg::OnBnClickedButton1()
{
CComVariant varArray;

// Get the array from the server
test.getSomething(&varArray);

// Attach the safe array
CComSafeArray <float> saFromVariant;
saFromVariant.Attach (varArray.parray);

a=saFromVariant.GetAt(0);
b=saFromVariant.GetAt(1);
c=saFromVariant.GetAt(2);
UpdateData(false);
}

My debugging tool, which is DevPartner gives me the following memory leak:

Memory Leak Exiting Program: Address 0x024101A0 (40) allocated by SafeArrayCreate.

The call stack gives me this lines of code causing the leak;
atlsafe.h 534
atlsafe.h 521
atlsafe.h 373
getSomething 195 (which is the line I have marked in the code above).

Can anyone help me out here? This leak is 40 bytes big, and that will become quite a large amount when the method in my real control is invoked approx. 5 times a second!!

Thanks for any help!

-- modified at 14:12 Thursday 29th June, 2006

Re: Memory leak

Zac Howland29-Jun-06 3:56

Zac Howland

29-Jun-06 3:56

pierre_ribery wrote:
varReturn.vt=VT_R4;

This is part of your problem. It should be the following:

varReturn.vt = VT_R4 | VT_ARRAY;

Otherwise, when the "smart" classes call ::ClearVariant, it won't be performing the proper cleanup procedure.

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

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