C / C++ / MFC Discussion Boards

Re: How do I pass a value to a class?

Bo Hunter4-Jan-04 8:38

Bo Hunter

4-Jan-04 8:38

Try

CFormatname(CWnd* pParent = NULL, CString myStr = NULL);

Thank You
Bo Hunter

Re: How do I pass a value to a class?

Bob Stanneveld4-Jan-04 23:16

Bob Stanneveld

4-Jan-04 23:16

Bo Hunter wrote:
CFormatname(CWnd* pParent = NULL, CString myStr = NULL);

Since myStr is not a pointer and NULL is a void pointer 0, the default argument isn't correct, but should be CFormatname(CWnd* pParent = NULL, CString myStr = "");.

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A professor knows a lot about little.
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Re: How do I pass a value to a class?

Michael Dunn4-Jan-04 8:56

Michael Dunn

4-Jan-04 8:56

The parameter lists in the constructor prototype and implementation don't match. Fix the prototype so the CString param is first.

--Mike--
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Re: How do I pass a value to a class?

Bo Hunter4-Jan-04 9:05

Bo Hunter

4-Jan-04 9:05

On my machine once you start default parameters from there
on out has to have defaults as well. Is this correct?

Thank You
Bo Hunter

Re: How do I pass a value to a class?

DanYELL4-Jan-04 9:43

DanYELL

4-Jan-04 9:43

Still stumped. I call the class like so:

CFormatname Dlg("ralph");

The constructor is:

CFormatname(CWnd* pParent = NULL, CString mystr = NULL); // constructor

and

CFormatname::CFormatname(CWnd* pParent /*=NULL*/, CString mystr)
: CDialog(CFormatname::IDD, pParent, mystr)
{
//{{AFX_DATA_INIT(CFormatname)
//}}AFX_DATA_INIT

thename = mystr;
}

and the errors are:

C:\Formatname.h(25) : error C2440: 'default argument' : cannot convert from 'const int' to 'class CString'
No constructor could take the source type, or constructor overload resolution was ambiguous

C:\Formatname.h(25) : error C2548: 'CFormatname::CFormatname' : missing default parameter for parameter 2

C:\Formatname.cpp(20) : error C2661: 'CDialog::CDialog' : no overloaded function takes 3 parameters

What perplexes me is the information that is added to the class by
Visual C++. It automatically adds 'CWnd* pParent /*=NULL*/'
and 'CFormatname::IDD' and I try to ignore those parameters and
mimic what I see in books, but it doesn't work.

Please, please, please any response anyone can give me will be
greatly appreciated.

Sincerely,
Danielle (an overworked graduate student)

Re: How do I pass a value to a class?

PJ Arends4-Jan-04 10:07

PJ Arends

4-Jan-04 10:07

The constructor you supplied is expecting the first parameter to be a CWnd*, and you are passing a string. Either change the constructor

CFormatname(CString mystr, CWnd* pParent = NULL)

or pass in a NULL pointer

CFormatname Dlg(NULL, "ralph");

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

Re: How do I pass a value to a class?

DanYELL4-Jan-04 15:04

DanYELL

4-Jan-04 15:04

Seems so obvious now (and it works). I appreciate the reply. I kept
wanting to ignore the 'CWnd* pParent = NULL' part.

One last question. For this part of the constructor:

CFormatname::CFormatname(CWnd* pParent /*=NULL*/, CString mystr)
: CDialog(CFormatname::IDD, pParent)
{
//{{AFX_DATA_INIT(CFormatname)
//}}AFX_DATA_INIT

name = mystr;
}

what exactly is CFormatname::IDD? What am I passing to CDialog?
pParent is just NULL and I know what :: means, but CFormatname::IDD
doesn't make sense.

Confused | :confused:

Re: How do I pass a value to a class?

Tim Smith4-Jan-04 15:41

Tim Smith

4-Jan-04 15:41

The IDD is the ID of the dialog. It is defined as a const in the class's H file.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: How do I pass a value to a class?

Shenthil4-Jan-04 20:52

Shenthil

4-Jan-04 20:52

Try This:

CFormatname(CString name,CWnd* pParent = NULL); // standard constructor

Shenthil

what is the definitive version of VC++

Ger Hayden4-Jan-04 7:15

Ger Hayden

4-Jan-04 7:15

I have been using the introductory edition of MS VC++ 6.0 that came with Ivor Hortons book. What is the current latest version? Confused | :confused:

Ger

Re: what is the definitive version of VC++

User 66584-Jan-04 7:58

User 6658

4-Jan-04 7:58

VC++ .NET 2003

modified 12-Sep-18 21:01pm.

Re: what is the definitive version of VC++

Michael Dunn4-Jan-04 8:57

Michael Dunn

4-Jan-04 8:57

If you mean what's the latest version of VC 6, it's service pack 5.

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invalid integer constant expression

ABean4-Jan-04 6:47

ABean

4-Jan-04 6:47

In a library that I downloaded I get an error on this line:

#if WIN32 && defined(_MSC_VER) && DEBUG

The sample app that came with the library compiles fine but when I use the library in my app it fails. I belive VC define those variables. So, its probably a configuration thing that I'm missing. (I compiled both projects in the Debug Configuration.)

Thanks for any ideas,
Albert

Re: invalid integer constant expression

PJ Arends4-Jan-04 10:48

PJ Arends

4-Jan-04 10:48

AFAIK it is complaining about DEBUG. VC defines _DEBUG (note the underscore). maybe the library or sample supplied defines DEBUG itself?

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

Re: invalid integer constant expression

ABean5-Jan-04 6:43

ABean

5-Jan-04 6:43

Thanks, that was it. DEBUG was defined in the sample program's project.

Winsock?

Stan the man4-Jan-04 6:35

Stan the man

4-Jan-04 6:35

I was wondering if there is a way to set the timeout for connecting? My app directly calls connect and if the server is OK then it will connect alright. If for example the address is wrong and it does not connect, it will hang there for many seconds.

One more thing, I am using WSAevents to signal read and etc. This is fine for me. However, I have a problem with using shutdown. It does not gracefully call the FD_CLOSE so that I can formally call closesocket. Has anyone seen this problem?

THanks in advance!

ToolBar close

Burl D4-Jan-04 6:24

Burl D

4-Jan-04 6:24

I have a class derived from CToolBar in a CFrame window. My problem is that I don't know how to tell if the user has closed the toolbar with the close button while it is floating. I have tried providing a OnClose message handler but it never gets called.
Any help would be greatly appreciated.
Thanks in advance.

Re: ToolBar close

PJ Arends4-Jan-04 10:55

PJ Arends

4-Jan-04 10:55

Maybe handle the WM_SYSCOMMAND message, looking for the SC_CLOSE command.

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

GDI drawing in layers

mirano4-Jan-04 5:52

mirano

4-Jan-04 5:52

Hi guys.

I want to draw in layers, so if anybody could give me a hint about that, I would really appreciate it. I want to be able to draw in multiple layers, so for instance if I am to erase a rectangle or any other more complex object, I would only discard a layer and repaint that object as altered, not having to redraw the background or anything else. It is something like in Photoshop when you draw on the layer and you bring it to the front, then you can delete the whole layer at any moment later.

I only need a general guidance, not the actual code.

Re: GDI drawing in layers

PJ Arends4-Jan-04 9:30

PJ Arends

4-Jan-04 9:30

Keep the layers in a vector of transparent bitmaps. draw the bitmaps on top of each other using TransparentBlt().

Sonork 100.11743 Chicken Little

"You're obviously a superstar." - Christian Graus about me - 12 Feb '03

Within you lies the power for good - Use it!

Sending a packet using PostMessage

__Cerb4-Jan-04 4:38

__Cerb

4-Jan-04 4:38

Let's say I have this piece of code...

CString strWndName = "My wnd";<br />
CString strClassName = "Wnd class";<br />
HWND hwnd = ::FindWindow(strClassName,strWndName);

Would it be possible to send a packet to hwnd using PostMessage?
If yes, which type of message should I send?

Thanks for help,

~Mike

Re: Sending a packet using PostMessage

Stefan Pedersen4-Jan-04 4:46

Stefan Pedersen

4-Jan-04 4:46

WM_COPYDATA[^] might fit your needs.

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I am coming home
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Re: Sending a packet using PostMessage

__Cerb4-Jan-04 5:33

__Cerb

4-Jan-04 5:33

Ok thanks.

Let's say I want to send the 0x68 packet.

COPYDATASTRUCT cds;
cds.lpData = NULL;
cds.cbData = 1;
cds.dwData = 0x68;

Would this work?

And what should I send as WParam? 0?

Thanks a lot for your help

~Mike

Re: Sending a packet using PostMessage

Gary R. Wheeler4-Jan-04 5:30

Gary R. Wheeler

4-Jan-04 5:30

I'm going to assume you are asking how you should use PostMessage to send a packet of information. "Which type of message" you should send depends on what you are trying to accomplish, which you haven't described. I'm also going to assume you are using MFC, and that you are trying to send a packet to a window created by your application.

If you are using PostMessage(), the message is placed on the window's message queue, and PostMessage() returns immediately. The window that receives the message may take some time before it processes the message. This means that the message will have to persist until the window gets around to looking at it. The easiest way to do this is to allocate your 'packet' on the heap, and deallocate it in the message handler. Here's an example:

#define MY_MESSAGE (WM_APP + 1)

class Packet {
public:
    Packet();
    ~Packet();
    // ... data members
    int m1;
};

...

// allocate a packet, set its contents

Packet *packet = new Packet;
packet->m1 = 123456;

// here's how you post a message

CString strWndName = "My wnd";
CString strClassName = "Wnd class";
HWND hwnd = ::FindWindow(strClassName,strWndName);

::PostMessage(hwnd,MY_MESSAGE,0,(LPARAM)packet);

This code sends your user-defined message MY_MESSAGE to the window with handle hwnd. Your handler for this message should be declared as follows:

afx_msg LRESULT OnMyMessage(WPARAM wParam,LPARAM lParam);

and it's implementation will look like the following:

BEGIN_MESSAGE_MAP( MyWindowClass, <window base class> )
...
ON_MESSAGE(MY_MESSAGE,OnMyMessage)
END_MESSAGE_MAP()
...

LRESULT MyWindowClass::OnMyMessage(WPARAM wParam,LPARAM lParam)
{
    Packet *packet = (Packet *)lParam;

    // ... use information in packet

    delete packet;

    return (LRESULT)0;
}

I hope this helps. If you are trying to send messages between applications, there are other methods of interprocess communication (named pipes, sockets, and so on) that are simpler.

Software Zen: delete this;

Re: Sending a packet using PostMessage

__Cerb4-Jan-04 5:45

__Cerb

4-Jan-04 5:45

Actually I am trying to send a packet to an online game.

That's why both your codes didn't work.

Thanks anyway, I hope you can help me

~Mike

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