C / C++ / MFC

Re: Accessing instances (fields) fron one class in another class

29-Mar-04 15:10

Christian,

Thanks again for your advice.

This is not for a project but for me to learn how sharing can be done within classes.

I also think I should be able to use Classes with Inheritance.

I will play with them. Thanks again.

Reni

Christian Graus29-Mar-04 15:11

Christian Graus

29-Mar-04 15:11

no worries. I guessed you were doing this to learn, which is why I'm trying to cover some best practice stuff, so you learn how to do things *well*. Good luck Smile | :)

Christian

I have drunk the cool-aid and found it wan and bitter. - Chris Maunder

Re: Accessing instances (fields) fron one class in another class

beamer_202029-Mar-04 15:28

Re: Accessing instances (fields) fron one class in another class

29-Mar-04 15:28

Christian,

Thanks again.

I agree with you. Making the instances public in a class is kind of "ugly".
I will be testing inherited classes.

Thanks,

Reni

Ravi Bhavnani29-Mar-04 12:52

Ravi Bhavnani

29-Mar-04 12:52

beamer_2020 wrote:
What do I have to do
How do I

The best suggestion I can give you is that you read the introductory chapters of the C++ book assigned by the instructor. If you have specific questions, you'll find the CP community will be happy to help you. But don't expect a CP member to do your homework for you.

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

Re: Accessing instances (fields) fron one class in another class

beamer_202029-Mar-04 14:56

Re: Accessing instances (fields) fron one class in another class

29-Mar-04 14:56

Ravi,

I wasn't expecting anyone to write code for me. I want to thank you for taking the time to reply.

Regards,

Reni

Renato

Ravi Bhavnani29-Mar-04 15:08

Ravi Bhavnani

29-Mar-04 15:08

Now I feel bad for my reply which appears harsher than I intended it to be. Sorry. Rose | [Rose]

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

Re: Accessing instances (fields) fron one class in another class

beamer_202029-Mar-04 15:19

how to read data from text file

29-Mar-04 15:19

Ravi,

Thanks again for your reply.

This is not for a school project. I'm just playing around with "classes" and wanted to experiment with sharing the instances (fields) between classes.

I replied to Christian and mentioned that I will probably try using "classes with inheritance". <class_specifier> <derived_class_name> : < base_class_name { additional members> };

Unfortunately some of the C++ books I have been reading, do not show you "interaction" between different classes at the beginning.

The other things I have seem is to make the instances public BUT it kinds of defects the beauty of C++.

Thanks again and please don't feel bad. I know of many people who want others to do everything for them.

Regards,

Reni

LudaLuda29-Mar-04 9:41

LudaLuda

29-Mar-04 9:41

Hey guys,

I'm having trouble reading an integer from a text file.

for example I have the following stored in a text file

------------ beginning of file------------excluding this line
H
88
------------ end of file------------excluding this line

and there are no spaces after any of the above words, each word is stored in one line.

I have an ifstream object that reads

char charVar;
int intVar;
inFile.read(reinterpret_cast<char*>(&charVar),sizeof(char));
cout <<"char value is : "<<charvar ;
infile.read(reinterpret_cast<char*="">(intVar),sizeof(int));
cout <<"int Var is : "<

PJ Arends29-Mar-04 9:59

PJ Arends

29-Mar-04 9:59

The number is stored in the file as text, so you have to read it in as text then transalte it into a number using atoi() ect.

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!

David Crow29-Mar-04 10:00

29-Mar-04 10:00

Per MSDN, read() reads the number of bytes specified by the second parameter. In this case, it reads 1 byte into charVar, but leaves the CRLF characters in the stream for the next call to read(). I think you need to use getline() instead.

LudaLuda wrote:
and I have to use the ios::binay method to open the file,

Why? From what you've shown, binary mode is not necessary.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

LudaLuda29-Mar-04 10:53

LudaLuda

29-Mar-04 10:53

okey guys I got that part to work.
Now I have another problem.

how do I move the pointer so that it points to the beginning of the next record location in the file. I have several records in the file.

Maxwell Chen29-Mar-04 15:17

Maxwell Chen

29-Mar-04 15:17

seekp(...);
seekg(...);

Maxwell Chen

David Crow30-Mar-04 2:06

Weird Character Allocation Problem.

30-Mar-04 2:06

LudaLuda wrote:
how do I move the pointer so that it points to the beginning of the next record location in the file. I have several records in the file.

That all depends on what a "record" is.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

HAHAHA_NEXT29-Mar-04 8:54

HAHAHA_NEXT

29-Mar-04 8:54

I have the following code:

TCHAR * ptszVersionInfo = _T(""); //Executes OK
ptszVersionInfo = new TCHAR[10]; //Executes OK
delete ptszVersionInfo; //Executes OK
ptszVersionInfo = _T("Anton"); //Executes OK
delete ptszVersionInfo; //Weird erro. From debug assert.It basically says there is an error with _CrtIsValidHeapPointer.

Now how come. (I am not very good with string allocation Dead | X|

Alexander ^M.,29-Mar-04 8:58

Alexander ^M.,

29-Mar-04 8:58

HAHAHA_NEXT wrote:
_T("Anton"); is a pointer to STATIC memory, u can't free it!

HAHAHA_NEXT wrote:
ptszVersionInfo = new TCHAR[10]; //Executes OK
delete ptszVersionInfo; //Executes OK this would rather be delete [] ptszVersionInfo;

Don't try it, just do it! Wink | ;-)

HAHAHA_NEXT29-Mar-04 9:00

HAHAHA_NEXT

29-Mar-04 9:00

Is there a way i can allocate _T("Anton") Into a dynamic memory ? because my code is all mixed up. (I allocate the string using both methods).

David Crow29-Mar-04 10:03

29-Mar-04 10:03

HAHAHA_NEXT wrote:
Is there a way i can allocate _T("Anton") Into a dynamic memory ?

This does not quite make sense, but I think what you want is:

TCHAR *p = new TCHAR[6];
_tcscpy(p, _T("Anton"));
...
delete [] p;

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

HAHAHA_NEXT29-Mar-04 10:08

HAHAHA_NEXT

29-Mar-04 10:08

Ths. It is exactly what i needed. The reason for this kind of weird stuff is because i can allocate the same string 2 ways:
the first is
p = "Anton"
and the second is

<br />
p = new TCHAR[6];<br />
_stprintf(p, ....)<br />

This will avoid me having different variable and one clean delete statement Smile | :)

How to get Dialog window to show updated value ?

Neville Franks29-Mar-04 10:33

Neville Franks

29-Mar-04 10:33

HAHAHA_NEXT wrote:
...
delete ptszVersionInfo; //Executes OK
ptszVersionInfo = _T("Anton"); //Executes OK
delete ptszVersionInfo;

Two problems:
1) You are using ptszVersionInfo after you've done a delete on it.
2) You are doing a second delete on a ptr that you've already done a delete on.

Neville Franks, Author of ED for Windows www.getsoft.com and coming soon: Surfulater www.surfulater.com

glweid29-Mar-04 8:53

glweid

29-Mar-04 8:53

I have a derived Dialog class - CGeneralStatus that has a CString variable. If I set the string before I create the CGeneralStatus dialog it is displayed OK. When I set this string to different value the value in the window does not get changed. Even if I close and reopen the dialog window the value does not change.

Any input is greatly appreciated !

------------------------------------------------------------------------

Application code:

void CFV3TaskMonApp::OnGeneralstatus()
{
if(IsShowingGeneral())
{
HideGeneral();
}
else
{
ShowGeneral(m_pMainWnd->GetActiveWindow());
}
}

void CFV3TaskMonApp::ShowGeneral(CWnd* parent)
{

if (!::IsWindow(*m_generalStatus))
{
m_generalStatus->Create(IDD_GeneralStatus, parent);
}

m_generalStatus->GeneralChanged(); // update the string
m_generalStatus->ShowWindow(1);
}

Code snippet to update the string value before calling ShowWindow(1):

void CGeneralStatus::GeneralChanged()
{
CString out;
out.Format("%d",m_app->m_numConnections);
m_connAttempts = out;

if (::IsWindow(this->GetSafeHwnd()))
{
::PostMessage(this->GetSafeHwnd(),UWM_STATUS_UPDATEGENERAL,0,0);
}

}

Re: How to get Dialog window to show updated value ?

David Crow29-Mar-04 9:54

Re: How to get Dialog window to show updated value ?

29-Mar-04 9:54

glweid wrote:
When I set this string to different value the value in the window does not get changed.

Even though you've assigned a value to a CString variable, you did not indicate how it was being displayed. Assuming it was an edit or static control, you simply need an appropriate control variable in the dialog's declaration (e.g., CEdit m_editnumConnections). When it comes time to display the value, simply call m_editnumConnections.SetWindowText().

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Anonymous29-Mar-04 10:20

Anonymous

29-Mar-04 10:20

My Dialog box only has the string variable (edit control - read only) box displayed, how do you declare a CEdit variable associated with that ?

I added a CEdit m_editnumCOnnections compiled it and passed the new string value to m_editnumConnections.SetWindowText() and it cores not finding a main window handle.

Thanks !

-----------
Code snip

// Dialog Data
//{{AFX_DATA(GeneralStatus)
enum { IDD = IDD_GeneralStatus };
CString m_connAttempts;
//}}AFX_DATA

Re: How to get Dialog window to show updated value ?

David Crow29-Mar-04 10:24

29-Mar-04 10:24

Anonymous wrote:
how do you declare a CEdit variable associated with that ?

ClassWizard.

Anonymous wrote:
...and it cores not finding a main window handle

What does "cores" mean in this context? Did you add the appropriate entry to DoDataExchange()? This is something that ClassWizard would do for you.

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

Power Management

Alexander ^M.,29-Mar-04 8:50

Alexander ^M.,

29-Mar-04 8:50

I want to suspent my display using a shortcut... no matter if vc++ or not.
Since I've never worked with power management I don't know how.
Any suggestions?

Thx

Don't try it, just do it! Wink | ;-)

Re: Power Management

David Crow29-Mar-04 9:49