Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

Assertion error when using CComboBox.AddString() method.

Posted on 2001-06-20
3
Medium Priority
?
478 Views
Last Modified: 2013-11-20
I have two Dialog frames and I am trying to populate a
CComboBox in the child dialog with elements from a CComboBox from the parent dialog. When I use the AddString
method when loading my child combobox I get an assertion
error at runtime in afwin2.nll at line 735 which seems to check if
the CComboBox is of the CWind class.

Here is the code I use in the parent to call the child:

// Create instance of child dialog
CAddEditDlg * AddProductDialog = new CAddEditDlg( this );

// This works ok so I know all attributes for
// child class have been created by now.
AddProductDialog->SetTitle("Add Product");

// Call method to load the child combobox passing the
// parent's filled combobox.
AddProductDialog->FillProductTypeComboBox
                  ( m_main_combo_control );

int nButtonClicked = AddProductDialog->DoModal();

Here is the method in the child class:

void CAddEditDlg::FillProductTypeComboBox
                  ( CComboBox & comboRef )
{
CString buffer;

for( int i=0; i < comboRef.GetCount(); i++ )
{
comboRef.GetLBText( i, buffer );

// This prints with the correct content
// for buffer.
AfxMessageBox("Adding " + buffer );

// Here is where the assertion error appears.
// I have tried even hard coding a string
// literal like "hello" and I still get the error.
m_combo_control.AddString( (LPCTSTR) buffer );
}

m_combo_control.SetCurSel( 0 );
}

Any help would be greatly appreciated ...

Thanks,
E.E.
 
0
Comment
Question by:eexposito
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
3 Comments
 
LVL 8

Accepted Solution

by:
VinExpert earned 225 total points
ID: 6212866
Hi,

U r calling AddString function of CComboBox before it has been created!!! so HWND will be NULL. To avoid that. Dont call ur AddProductDialog->FillProductTypeComboBox
( m_main_combo_control ); function from the parent. Instead, map WM_INITDIALOG to ur child dialog and in that function after the base class OnInitDialog() call, call ur function FillProductTypeComboBox(...) there. That should solve ur prob.

Try it out.
VinExpert

0
 
LVL 42

Expert Comment

by:Meir Rivkin
ID: 6213449
>>AddProductDialog->FillProductTypeComboBox
                 ( m_main_combo_control );

>>int nButtonClicked = AddProductDialog->DoModal();

u need to switch the order of those two line codes and change its syntax a little bit.
u send a reference control to a dialog which wasn't been created yet.
since u use modal dialog and not modaless
(using ->Create) the assertion took place.

>>CAddEditDlg * AddProductDialog = new CAddEditDlg( this );

- since u send "this" pointer here, i believe that u can use this pointer to get to the m_main_combo_control which is a data member.

briefly, u need to save to this pointer as follow:
CAddEditDlg::CAddEditDlg(CParentDlg* pDlg)
{
m_parentDlg = pDlg;
}

now u can use parentDlg pointer to fill the combo box as follow:

CString buffer;

for( int i=0; i < comboRef.GetCount(); i++ )
{
comboRef.GetLBText( i, buffer );

// This prints with the correct content
// for buffer.
AfxMessageBox("Adding " + buffer );

// Here is where the assertion error appears.
// I have tried even hard coding a string
// literal like "hello" and I still get the error.
m_parentDlg->m_main_combo_control.
.AddString( (LPCTSTR) buffer );
}

m_parentDlg->m_main_combo_control.
.SetCurSel( 0 );


good luck
0
 
LVL 2

Expert Comment

by:Chandra V
ID: 6213840
The problem is adding the items before creating the window

You can simply do the following:

As you are passing the this pointer to the dialog
-> CAddEditDlg * AddProductDialog = new CAddEditDlg( this );

Add a member variable pointer of type parent class ( i.e, suppose - CMainFrame* pFrame;) then in your constructor of CAddEditDlg equate the parameter passed to the member declared (i.e, pFrame = pParent).

Then in the on init dialog do the same as you are doing in the 'FillProductType' combobox by just replacing m_combo_control with pFrame->m_combo_control, and don'comment out the call in the parent

// Call method to load the child combobox passing the
// parent's filled combobox.
//AddProductDialog->FillProductTypeComboBox
                 ( m_main_combo_control );
0

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Have you tried to learn about Unicode, UTF-8, and multibyte text encoding and all the articles are just too "academic" or too technical? This article aims to make the whole topic easy for just about anyone to understand.
Ready to get certified? Check out some courses that help you prepare for third-party exams.
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …

604 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question