Commonly Overridden Member Functions

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The following table lists the most likely member functions to override in your CDialog-derived class.

Commonly Overridden Member Functions of Class CDialog

Member function	Message it responds to	Purpose of the override
OnInitDialog	WM_INITDIALOG	Initialize the dialog box’s controls.
OnOK	BN_CLICKED for button IDOK	Respond when the user clicks the OK button.
OnCancel	BN_CLICKED for button IDCANCEL	Respond when the user clicks the Cancel button.

OnInitDialog, OnOK, and OnCancel are virtual functions. To override them, you declare an overriding function in your derived dialog class using ClassWizard. In these cases, ClassWizard will not add any message-map entries because they are not necessary.

OnInitDialog is called just before the dialog box is displayed. You must call the default OnInitDialog handler from your override — usually as the first action in the handler. By default, OnInitDialog returns TRUE to indicate that the focus should be set to the first control in the dialog box.

OnOK is typically overridden for modeless but not modal dialog boxes. If you override this handler for a modal dialog box, call the base class version from your override — to ensure that EndDialog is called — or call EndDialog yourself.

OnCancel is usually overridden for modeless dialog boxes.

For more information about these member functions, see class CDialog in the Class Library Reference and the discussion on Life Cycle of a Dialog Box.