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LIstbox Question -> adding items after Initialization

qualvis
qualvis asked
on
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Last Modified: 2013-11-20
Hi,

How can I add something to a listbox, AFTER it's initialized?
First, I use this code:

BOOL CDialog1::OnInitDialog()
{
      CDialog::OnInitDialog();
      m_ListBox.AddString("jef");
      return true      ;
}

and this works fine. But I want to be able to add other items afterwards (to be precise, I would like to be able to show the user which webcams are available.)

So  I made a function:

void CCamDialog::AddListBox()
{
      m_CamList->AddString("camera");
}


But this gives an error (debg assertion failed).

any ideas?

thanks
Tim Magnus

Comment
Watch Question

What is m_CamList?
If this is a pointer to list box
Plz do this in your OnInitDialog
m_CamList = (CListBox*)GetDlgItem(IDC_LIST1);
//IDC_LIST1 is the id for your list box
else if it is added through class wizard as a control member
m_CamList.AddString("camera") will work (as you do in m_ListBox.AddString)

-Lakshman

Author

Commented:
Sorry for that, Guess I copied it wrong (I was trying to make it work in an other application)
It should be

BOOL CDialog1::OnInitDialog()
{
CDialog::OnInitDialog();
m_ListBox.AddString("jef");
return true ;
}

and


void CDialog1::AddListBox()
{
m_ListBox.AddString("camera");
}
If you added m_ListBox member through the class wizard as control variable the code in OnInitDialog() should work fine.

If you are calling AddListBox() after dialog initialization that also should work fine.
I hope you are not calling this method in  OnCreate method or Constructor.

-Lakshman
AndyAinscowFreelance programmer / Consultant
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Commented:
How is the AddListBox called?  After your dialog is visible?
There is nothing wrong with your code as such, it should work.

However if you are trying something like
CDialog1 dlg(this);
dlg.AddListBox();
dlg.DoModal();
then it will fail as your listbox doesn't exist at the time you call the AddListBox.

In an instance like this you would need to add the strings to an array in CDialog1 and the list box is filled with the contents of the array in the OnInitDialog fn.

Author

Commented:
Addlistbox was indeed being called like this:

void CDialogTestApp::OnTest1()
{
      CDialog1 d1;      
      d1.AddString();
      d1.DoModal();      
}

(with ontest1 being an eventhandler when i press a menuitem)

But how should I do it then? Should I make an extra constructor which receives an array, and passes it on OnInitDialog?

thanks for your help btw! It's very much appreciated...
Freelance programmer / Consultant
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Commented:
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Author

Commented:
They should put an edit button on this forum

it's called like this obviously:

void CDialogTestApp::OnTest1()
{
     CDialog1 d1;    
     d1.AddListBox();   // AddLIstbox instead of Addstring of course
     d1.DoModal();    
}
AndyAinscowFreelance programmer / Consultant
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Commented:
My previous comment still applies.

Author

Commented:
Yes, that should do the trick I think. (why couldn't I come up with that)

Thank you very very much!

When I become a very talented and Professional programmer, I hope I can help you out once too ;-)

Tim Magnus

Author

Commented:
Brilliant, it works!

Thank you!
AndyAinscowFreelance programmer / Consultant
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Commented:
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