SAMPLE: Filling List Box Using MFC's DDX Facility

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Edition, version 4.0

This is the 32-bit version of this sample.

SUMMARY

The Lstddx32 sample illustrates a technique for filling both an ordinary list box control and the list box portion of a combo box control with data, and using the Microsoft Foundation Class (MFC) Dialog Data Exchange (DDX) facility to return the selection.

The following file is available for download from the Microsoft Software Library:

 ~ Lstddx32.exe (size: 35379 bytes) 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

A common misconception with regard to DDX is that assigning a value to a DDX variable will cause that data to be loaded into a control. This does in fact happen for edit controls, but not for list box controls. In order to add items to a list box the dialog class must use the CListBox::AddString() or CComboBox::AddString() functions. Doing this involves several steps which are illustrated by this sample.

The sample itself was initially created as an MDI application using AppWizard from Visual C++ version 1.0. AppStudio was then used to create a dialog which contains OK and Cancel button plus an edit control (IDC_EDIT1), a combo control (IDC_COMBO1), and a list box control (IDC_LIST1). The Class Wizard was used to create a class CDialog1 based on CDialog. The files dialog1.h and dialog1.cpp contain the code for this class. Class Wizard was also used to add DDX member variables m_edit1, m_combo1, and m_list1 to dialog1.h. A menu item was added to the view menu (IDR_LIST_DTYPE) using AppStudio, and a message handler added which will call the dialog when the menu item was selected.

The Readme.txt file included with the sample explains in more detail how the list boxes are initialized and how data is passed between the calling routine and the dialog procedure.