The DDX_CBString function manages the transfer of CString data between the edit control of a combo box control in a dialog box, form view, or control view object and a CString data member of the dialog box, form view, or control view object.
A pointer to a CDataExchange object. The framework supplies this object to establish the context of the data exchange, including its direction.
The resource ID of the combo box control associated with the control property.
A reference to a member variable of the dialog box, form view, or control view object with which data is exchanged.
When DDX_CBString is called, value is set to the current combo box selection. If no item is selected, value is set to a string of zero length.
If the combo box is a drop-down list box, the value exchanged is limited to 255 characters.
For more information about DDX, see Dialog Data Exchange and Validation.