Re: Combo Box Problem - C / C++ / MFC Discussion Boards

mvworld21-Nov-01 14:23

21-Nov-01 14:23

Hello,

Well I have this funny problem. I want to add items to my combo box in a child dialog box from my parent dialog box just before the child is shown.

To do this I have the following line

ChildDlg.m_ComboBox.AddString("Some Text");

I even tried

ChildDlg.m_ComboBox.InsertString(0, "Some Text");

I made sure too that the member variable m_ComboBox in the class ChildDlg referred to the contro (not the value) of my Combo box.

What is wrong?

Thanks,
Mike

Re: Combo Box Problem

Sidney Chong21-Nov-01 14:42

Sidney Chong

21-Nov-01 14:42

Hi Mike, you have to tell us what the funny problem is. e.g. the app crashed (hm... thats really helpful), combo box not being updated, etc...

Oh, and in which message handler are you calling the "AddString"/"InsertString" methods?

Re: Combo Box Problem

mvworld21-Nov-01 14:47

mvworld

21-Nov-01 14:47

Well the application crashes.

I have a main dialog box and in one of the functions I create a child dialog box which has the member variable m_ComboBox as public.

So in my main dialog box I have

CChildDialog ChildDlg;
ChildDlg.m_ComboBox.AddString("Some Text");
ChildDlg.DoModal();

And then when I run this application, it crashes.

So to test again I tried to Add a string to the combobox in the constructor of my child dialog but the application still crashed!

What shall I do?

Re: Combo Box Problem

Masaaki Onishi21-Nov-01 15:05

Masaaki Onishi

21-Nov-01 15:05

Hello, the codegurus around the world.;)

I think that DoModal() must call OnInitDialog() in CChildDialog.
So, the location between ChilDlg and DoModal() will not
create ComboBox yet.

So, I think that you had better put AddString(...) in OnInitDialog()
of CChildDialog.

CChildDialog ChildDlg;
ChildDlg.m_string = _T("Some Text");
ChildDlg.DoModal();

And in OnInitDialog() of ChildDlg

//Already, m_string is updated!
m_ComboBox.AddString (m_string);

Have a nice day!

-Masaaki Onishi-

Re: Combo Box Problem

mvworld21-Nov-01 15:13

mvworld

21-Nov-01 15:13

But there is no OnInitDialog() in my child dialog class!!
Even when I tried to override OnInitDialog (hoping it was there in CDialog) it did not have it already defined in the base class.

Re: WM_INITDIALOG

Masaaki Onishi21-Nov-01 17:33

Masaaki Onishi

21-Nov-01 17:33

Hello, the codegurus around the world.;)

You can manually add OnInitDialog() with WM_INITDIALOG.

Or use WM_INITDIALOG by the class wizard, and this automatically
generates the message and its handler in CChildDlg class. Roll eyes | :rolleyes:

Have a nice day!

-Masaaki Onishi-

Re: Combo Box Problem

Sidney Chong21-Nov-01 15:21

Sidney Chong

21-Nov-01 15:21

Well, here's the problem... the control hasn't been created yet! MFC's UI classes are really wrappers around the Win32 equivalents. Having constructed the class does not imply that the corresponding controls have been created. So what you want to do is the following:

(1) create a data member (a string or an array of strings maybe?) in your child dialog to hold the data thats going into the combo box.
(2) set this data member after you have created the child dialog but before the call to DoModal (DUH!)
(3) override OnInitDialog of the child dialog (or OnCreate if its not a dialog) to pass this data into the combo box using AddString or InsertString, whichever you prefer.

--update--
Oh bugger, Masaaki beat me to it..... Poke tongue | ;-P

my link sux! Mad | :mad:

Re: Combo Box Problem

mvworld21-Nov-01 15:49

mvworld

21-Nov-01 15:49

Hey,

I did as you told me. But now the application still mysteriously crashes.

What I want to do is that just before the child appears, a function in the main dialog box (the parent) provides the child with stuff the child needs to show in the combo box.

Since in the child I have a pointer to the parent, so I used it to call the function which should provide the child with the data for the combo box.
But somehow the application crashes!

Are we allowed to call other functions inside the OnInitDialog/OnInitInstance?

Re: Combo Box Problem

Sidney Chong21-Nov-01 16:46

Sidney Chong

21-Nov-01 16:46

Yes you are allowed to call other functions in those methods. But note that in your particular case, you should be using OnInitDialog instead of OnInitInstance

-- sample pulled from MSDN --
IMPT NOTE: Remember to call the base class' OnInitDialog as shown in the sample!!

// MyDialog.cpp
#include "MyDialog.h"

BOOL CMyDialog::OnInitDialog() 
{
   //call the base implementation first!
   CDialog::OnInitDialog(); 
   
   // TODO: Add extra initialization here
   m_cMyEdit.SetWindowText("My Name"); // Initialize control values
   m_cMyList.ShowWindow(SW_HIDE);      // Show or hide a control, etc.

   return TRUE;   // return TRUE unless you set the focus to a control
                  // EXCEPTION: OCX Property Pages should return FALSE
}

Re: Combo Box Problem

Michael Dunn21-Nov-01 17:47

Michael Dunn

21-Nov-01 17:47

The other replies have been hit-and-miss, so I'll summarize here.

You're confusing the dialog C++ object with the dialog window. The window does not get created until you call DoModal(). There is no dialog, and thus no controls to manipulate, before the DoModal() call.

The proper way is to override OnInitDialog() in your dialog's C++ class. At the time WM_INITDIALOG is sent, the window and all child controls have been created, but not yet shown. So at that time, it's fine to set up the controls.

--Mike--
http://home.inreach.com/mdunn/
While I can't be correct on all matters, I can make the reassuring claim that where I am inaccurate, I am at least definitively inaccurate.
Heart | [heart]

your

with

and

Sonork ID - 100.10414 AcidHelm

Re: Combo Box Problem

luckylourson21-Nov-01 22:07

luckylourson

21-Nov-01 22:07

I don't understand why you don't fill the combo box after the DoModal()..It's not a properly way but it is sure.

Re: Hum, a little different!

Masaaki Onishi22-Nov-01 4:36

Masaaki Onishi

22-Nov-01 4:36

Hello, the codegurus around the world.;)

Fisrt of all, we are talking about the initalization of the string
in ComboBox.
And, OnInitDialog() in the parent dialog of ComboBox is best location
to do that.

Second, the location after DoModal() means that ChildDlg will disapper
since ChildDlg is the modal dialog like the message box.
This means that as long as ChildDlg is opened (DoModal still works),
we can add the new strings to this ComboBox inside or outside this dialog
as long as we can get the right CWnd of ComboBox. Roll eyes | :rolleyes:

Have a nice day!

-Masaaki Onishi-

Changing the font in a Combo Box?

Chambers21-Nov-01 9:51

Chambers

21-Nov-01 9:51

Hi All, just a quick one - How can I change the font type and size that is used to display text in a combo box? At the moment my MDI App has one located in the MainFrame toolbar, but because the Arial font looks so pants its made my app look as though its been designed for Windows 3.x. Please help make my app look better,

Cheers Guys,
Alan. Big Grin | :-D

"When I left you I was but the learner, now I am the Master" - Darth Vader Mad | :mad:

Re: Changing the font in a Combo Box?

Nemanja Trifunovic21-Nov-01 10:06

Nemanja Trifunovic

21-Nov-01 10:06

Just as with any other window:

<br />
void CWnd::SetFont( CFont* pFont, BOOL bRedraw = TRUE );<br />

I vote pro drink Beer | [beer]

Re: Changing the font in a Combo Box?

Chambers21-Nov-01 12:50

Chambers

21-Nov-01 12:50

Thanks for the response, however, I have inevitably reached a problem and my efforts have gone to no avail, please help. This is the code that has resulted from my patheticness in an attempt to get it going :

int CMainFrame::OnCreate(etc..)

//Toolbar definition.

stdFont.CreateFont(25,12,10,10,FW_THIN,FALSE,FALSE,FALSE,ANSI_CHARSET,OUT_OUTLINE_PRECIS,CLIP_DEFAULT_PRECIS,PROOF_QUALITY,0,"Times New Roman");
SetFont(&stdFont, TRUE);

//ComboBox setup and displaying code.

Can you see where I`m going wrong with this? I`ve tried different values for the third and forth arguments, but the combo box still uses the same crappy font to display the strings!!! Also I have checked the return value of the CreateFont function and its 1, so it must be doing something? Any advice on my failings would be hugely welcomed.

Thanks again,
Alan. Confused | :confused:

"When I left you I was but the learner, now I am the Master" - Darth Vader Mad | :mad:

Re: Changing the font in a Combo Box?

Derek Waters21-Nov-01 12:55

Derek Waters

21-Nov-01 12:55

Is stdFont defined locally to the OnCreate function, or is a member variable? If it's defined locally, then when OnCreate finishes, the CFont object is destroyed, so you end up with the crappy default font. I don't know if this is the problem, but I know I've done this a lot of times!

------------------------
Derek Waters
derek@lj-oz.com

Re: Changing the font in a Combo Box?

Chambers22-Nov-01 1:33

Chambers

22-Nov-01 1:33

I found the answer, at last. I had been changing the MainFrame's standard font, and it was not being reflected in the combo box. As soon as I changed my code to m_ctlCombo.SetFont(&stdFont, TRUE), it worked! amazing! Many thanks to those of you who offered their advice on this, I very much appreciate it.

Cheers,
Alan.

"When I left you I was but the learner, now I am the Master" - Darth Vader Mad | :mad:

Re: Changing the font in a Combo Box?

22-Nov-01 1:46

Here's some code for changing the font in a combobox...

LOGFONT lf = { 0 };
(void)lstrcpy( lf.lfFaceName, _T("MS Sans Serif") );
lf.lfHeight = -MulDiv( 10, GetDeviceCaps( GetDC()->m_hDC, LOGPIXELSY ), 72 );
VERIFY( m_font.CreateFontIndirect( &lf ) );
m_ctlCombo.SetFont( &m_font );

Best regards,
Mark
www.mjsoft.co.uk

Towers of Hanoi

Zach21-Nov-01 9:45

Zach

21-Nov-01 9:45

Hi
I'm engaged in a project involving writting c code to solve the towers of hanoi problem as fast as possible. My goal is to be able to solve it with 30 rings in 1 second. Does anyone know of specific compiler command line switches to compile something to run faster or any good tutorials to assembler?

Zach

Re: Towers of Hanoi

Christian Graus21-Nov-01 10:18

Christian Graus

21-Nov-01 10:18

I believe that optimise for size actually results in faster code a lot of the time. Look up /O switches in MSDN for the full list of available switch options.

The John Robbins book 'Debugging Applications' by M$ Press has an assembler section that is quite good, but as he says, it is usually doubtful that you'd outdo the compiler nowadays.

Christian

After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001

Re: Towers of Hanoi

Rick York21-Nov-01 11:25

Rick York

21-Nov-01 11:25

I use the optimize for speed option most of time and I find that it also reduces the size considerably. I have run into optimizer bugs many times with heavy floating point code though so I have learned to be careful.

Re: Towers of Hanoi

Andrew Peace21-Nov-01 14:37

Andrew Peace

21-Nov-01 14:37

The Towers of Hanoi problem is recursive - make sure you've implemented it properly, then optimise for size. A key optimisation might be taking the invariant out of your tight inner loops.

--
Andrew.

Weird Problem

Peter Liddle21-Nov-01 8:50

Peter Liddle

21-Nov-01 8:50

Hey Guys

I am totally stuck i have a structure that is working fine of 3 TCHAR arrays but as soon as i add a 4th TCHAR array the structure causes the program to crash has anyonegot any ideas.

This is the Structure

struct CertificateNames
{
TCHAR sCommonName[STRING_LENGTH];
TCHAR sIssuerName[STRING_LENGTH];
TCHAR sFriendlyName[STRING_LENGTH];
};

The only thing i can think is that there is a set size for a structure.

STRING_LENGTH = 256

Cheers Guys
Peter

Re: Weird Problem

Christian Graus21-Nov-01 8:58

Christian Graus

21-Nov-01 8:58

You're obviously able to create a structure of four TCHAR's, you need to show us some code where it crashes to try and fix the problem.

Christian

After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001

Re: Weird Problem

Peter Liddle21-Nov-01 11:32

Peter Liddle

21-Nov-01 11:32

This is the Structure

struct CertificateNames
{
CERT_INFO CertID;
TCHAR sCommonName[STRING_LENGTH];
TCHAR sIssuerName[STRING_LENGTH];
TCHAR sFriendlyName[STRING_LENGTH];
};

As for what happens to it i only write values into the string arrays.

Cheers
Peter

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