Re: Variables under different class - C / C++ / MFC Discussion Boards

OOP Question - Passing Data Between Objects

AJ12320-Oct-01 13:35

20-Oct-01 13:35

Hi,

I have a scenario, where i have an object say 'A' which has a member varible which is another object say 'B'.

I want to be able to pass data from object B Up To A. Without B have any knowledge of A.

Anyone any sugestion, Surely this must be a regular task.

Cheer

Richard

Re: OOP Question - Passing Data Between Objects

Ben Burnett21-Oct-01 6:15

Ben Burnett

21-Oct-01 6:15

// class B ////////<br />
class B {<br />
<br />
public:<br />
int getData () { return data; }<br />
<br />
private:<br />
int data; // B's data<br />
<br />
};<br />
<br />
// class A ////////<br />
class A {<br />
<br />
public:<br />
void printBData () { <br />
<br />
    int data = myB.getData ();<br />
    cout << "B's data: " << data << nl;<br />
<br />
}<br />
<br />
private:<br />
B myB;<br />
<br />
};

Ben Burnett

"It's all absolutely devastatingly true -- except the bits that are lies"
- Douglas Adams

Re: OOP Question - Passing Data Between Objects

Andrew Peace21-Oct-01 11:05

Andrew Peace

21-Oct-01 11:05

There are two methods that you could consider;

1. Instead of having B push the information to A, why not have A query B for the information when it's needed?

2. Use a proxy class. Thus, B and A will know about C, and B will use C to pass information to A. This is similar to the observer pattern (I think?) - there's a good articleon this site about the observer pattern but I can't remember exactly where now.

--
Andrew.

Taskbar?

MaTrIX2k220-Oct-01 9:58

MaTrIX2k2

20-Oct-01 9:58

How can i make a taskbar in my app?

Re: Taskbar?

Michael P Butler20-Oct-01 11:13

Michael P Butler

20-Oct-01 11:13

Have a look at CDialogBar or have a browse here http://www.codeproject.com/docking/

Of course if you mean something else, post a bit more detail.

Michael Smile | :)

Re: Taskbar?

MaTrIX2k220-Oct-01 11:46

MaTrIX2k2

20-Oct-01 11:46

I mean a taskbar in the app 'coz when i minimize my dialogs don't keep a little window, and stay in a bar just like mIRC and other programs.

Variables under different class

Kuniva20-Oct-01 6:52

Kuniva

20-Oct-01 6:52

I have two seperate classes for two different dialogs in MFC. Now i want to acces the variables of one dialog in the code of the other class of the other dialog. How do i do this?

Thanx

Kuniva

Want, take, have.

Re: Variables under different class

Michael P Butler20-Oct-01 11:17

Michael P Butler

20-Oct-01 11:17

The easiest way is to declare the variables as public members of the class and then access them in the usual c++ way,

void CDialog1::Test()
{
    CDialog2 dlg;
     
    // set flag
    dlg.m_bTestFlag = TRUE;
    int nRet = dlg.DoModal();

    if(nRet == IDOK)
    {
       // get new state
       BOOL bTest = dlg.m_bTestFlag;
    }
}

Find a string in a file

Maer72720-Oct-01 3:02

Maer727

20-Oct-01 3:02

How to find a string in a file?
Are there any VC functions that I can use directly?

Can you help?

Thanks,
Maer

Re: Find a string in a file

NormDroid20-Oct-01 3:28

NormDroid

20-Oct-01 3:28

If your file is a text file which I assume it is, try this...

CStdioFile file;
if (!file.Open("c:\\file.txt", CFile::modeRead))
return;

CString str;
while (file.ReadString(str))
{
if (str.Find("Search String) != -1)
{
TRACE("Found it!");
}
}

Normski - Professional Windows Programmer

Re: Find a string in a file

Maer72720-Oct-01 3:58

Maer727

20-Oct-01 3:58

Hi, Normski!

Thanks for your reply! It is the one I am looking for!

Have a nice weekend!
Maer

Re: Find a string in a file

NormDroid20-Oct-01 4:02

NormDroid

20-Oct-01 4:02

and you my friend!

Normski - Professional Windows Programmer

Re: Find a string in a file

Maer72720-Oct-01 19:12

Maer727

20-Oct-01 19:12

Thanks pal!

- My weekend is not as good as yours. My girl is in another city. 200KMs away. We just chat throught the net. ^__^

Regards,
Maer

Passing Pointers To Function In C++

AJ12320-Oct-01 2:26

AJ123

20-Oct-01 2:26

Hi,

What I want, is to pass a function which is a member of one object into the contructor of a new object it declares. So the new object can then call it.

Keep getting errors along the lines of:

error C2664: '__thiscall CTest::CTest(void (__cdecl *)(char *))' : cannot convert parameter 1 from 'void (char *)' to 'void (__cdecl *)(char *)'

Can Anyone offer Any Advice, it work if i declare the function as a static.

Guess it's a c++/c isssue. The function prototype is for a standard c function where i want it to be for a class memeber function

Or is this the sort of thing that should be done through some Object Orientated Programming principle.

Thanks, Much Appreciated

Richard Jackson

Re: Passing Pointers To Function In C++

Tim Deveaux20-Oct-01 5:04

Tim Deveaux

20-Oct-01 5:04

Yes, you've pretty much got it - the non-obvious part is the passing of the implicit this pointer to member functions, which alters the function signature of those functions.

Filter on thiscall in this forum for more info. There's also a bit in the FAQ on using member fns as C (Windows) callbacks.

*** Multiple Client Socket in MFC ***

Salman Ahmad Khan20-Oct-01 0:24

Salman Ahmad Khan

20-Oct-01 0:24

Hi,
in MFC using CSocket or CAsyncSocket following approach can set communication between a client socket and a Connecting socket on server side.

ListeningSocket.Accept ( ConnectingSocket );

Confused | :confused:

Problem, How will multiple clients be implemented?

Cool | :cool:

I have the clue that Link List, Array, Threads might be used for creating multiple connections with multiple clients.
like ListenSock.Accept ( ConnectSock[i] );

Confused | :confused:

BUT how will the messages be handeled. How will one connecting socket differentiate form otherones message.

Cry | :((

PLZ HELP !!!!!

RawCoder

Re: *** Multiple Client Socket in MFC ***

NormDroid20-Oct-01 0:35

NormDroid

20-Oct-01 0:35

I would strongly recommend NOT using the MFC implementation wrappers for sockets.
The best and *orthodox* way to to use raw sockets WSAEvent etc.
A very good book to but describing the programming of sockets for windows is
"Winsock 2.0" - By Lewis Napper.

Re: *** Multiple Client Socket in MFC ***

Salman Ahmad Khan20-Oct-01 1:10

Salman Ahmad Khan

20-Oct-01 1:10

I really need to do it in MFC due to time constraint.

RawCoder

Re:First, learn TCP/IP!

Masaaki Onishi20-Oct-01 11:51

Masaaki Onishi

20-Oct-01 11:51

Hello, the codegurus around the world.

First, you had better understand the concept of TCP/IP.
Server idnetifies the client with IP address and the port number.

This means that the client machine is assigned to the different IP address,
so server can understand the different client with IP address.
So, you may need the other code to restore IP addresses with the current access to the server, and differntiate the incoming socket with IP address.
(I think that this works, but I never implement this level of code. Dead | X|

)

Have a nice day!

-Masaaki Onishi-

Re: *** Multiple Client Socket in MFC ***

20-Oct-01 12:38

as far as i know, what can be done is for each client spawn a thread and all the window messages will be handled in that thread. so by this way multiple clients can be done. Sure u can do this using MFC. u can get a lot of source code in internet. may be have a look at www.naughter.com

For learning c++, which one will be you choice?

flying20-Oct-01 0:05

flying

20-Oct-01 0:05

"The C++ Programming Language" or "C++ Primer" and why?

Re: For learning c++, which one will be you choice?

NormDroid20-Oct-01 0:37

NormDroid

20-Oct-01 0:37

Both,
The primer is elegant in its simplicity describing C++, after you got over the learning curve, "The C++ programming languauge" become your bible, and is much more detailed.

Looking support for c++ in Linux

Gaurav Lambole20-Oct-01 0:01

Gaurav Lambole

20-Oct-01 0:01

is there any support for c++ in Linux,

I just want to develop some word pad kind of stuff in c++ for Linux.....

can you give me any info about it....

Gaurav Lambole
webdunia.com (India) pvt.ltd.

Re: Looking support for c++ in Linux

markkuk21-Oct-01 19:47

markkuk

21-Oct-01 19:47

Yes, gcc (Gnu Compiler Collection) contains a very good implementation of C++. It is included in all complete Linux distributions, but it might not be installed by default. There are also various GUI front ends to the compiler, e.g. KDevelop.

How to destroy Array of Controls

19-Oct-01 21:24

I have to give a data tip on every record(each recod contains three points) on mygraph.For this i am creating
Button controls for every point in for loop as like

MyFuntion(){
for(firstrecord,somerecords(nearly25),lastrecord)
{
CButton *pCon=new CButton;//start point
CButton *pCon1=new CButton;//peak point
CButton *pCon2=new CButton;//end point

pCon.Create(_TEXT(""),WS_VISIBLE|BS_FLAT,CRect,this,Number)

pCon1.Create(_TEXT(""),WS_VISIBLE|BS_FLAT,CRect,this,Number)

pCon2.Create(_TEXT(""),WS_VISIBLE|BS_FLAT,CRect,this,Number)

m_datatip.AddTip(Text,pCon,Number);
m_datatip.AddTip(Text,pCon1,Number);
m_datatip.AddTip(Text,pCon2,Number);

}
}

I am calling this function from OnPaint.
For very first this code is working exactly.When ever
i am calling this function next time the controls not destroying.

I used "delete [] control" ,"delete control" in various places in my function and i didn't get the solution.

Please help me ,
Where can I delete these created controls for callling the Myfunction next time. Rose | [Rose]

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