The DDX_CBStringExact function manages the transfer of CString data between the edit control of a list 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.
When DDX_LBStringExact is called to transfer data to a list box control, the first item in the control that matches value is selected. (To match just a prefix rather than the entire item, use DDX_LBString.) If there are no matches, no items are selected. The matching is case-insensitive.
When DDX_CBStringExact is called to transfer data from a list box control, value is set to the current list box selection. If no item is selected, value is set to a string of zero length.
If the list 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.