hi,
are you in dialog box and you are speking of edit control?
Suppose yes; you have a control call it MASTER and another
call it SLAVE.
Define for them CString Member Variable, call them cMaster and cSlave
In the Master you have to check the value: you can do it when you leave it (by tab or mouse) or while the value is changing: in 1st case define in message map, the event
EN_KILLFOCUS, in te 2nd EN_CHANGE. In the routine you define
associated with this event, call the UpdateData( TRUE ):
this will update the variable cMaster.
Always in this routine, do your consideration, build the
cSlave variable and call the UpdateData( FALSE ):
this will update all controls and then also SLAVE.
If you don't wont define Member variables, use system call
SetWindowText and GetWindowText together with GetDlgItem.
ciao
vittorio