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' This example uses DOEVENTS to yield to other operating environment events
' that may be occurring at the same time as a CPU-intensive FOR...NEXT loop
' in Visual Basic processing. Click the form to start the DOEVENTS loop.
 
' To try this example:
' 1. Choose New Project from the File menu
' 2. Choose New Form from the File menu to create a form
' 3. Press Alt+F4 to return to the programming environment
' 4. Copy the code example below to the form module
' 5. Press F5 to run the example
 
 DECLARE SUB DoEventsDemo ()
 
 SUB DoEventsDemo ()
     Msg$ = "A FOR...NEXT loop simulates a CPU intensive operation. "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "DOEVENTS is not used the first time the loop "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "executes. As a result, you are unable to do "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "anything else until the loop is finished. Choose "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "OK and try to select another window before the beep."
     MSGBOX Msg$
     FOR I% = 1 TO 5000                      ' Start 1st loop
          N% = INT(5000 * RND + 1)           ' Generate random number
     NEXT I%                                 ' Increment loop counter
     BEEP                                    ' Notify user 1st loop is done
     Msg$ = "DOEVENTS is used the second time the loop executes causing "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "it to yield control to other events that may occur "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "while the loop is executing. The processing appears "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + _
     "to be running in the background. Now choose OK and "
     Msg$ = Msg$ + CHR$(10) + CHR$(13) + "try to select another window."
     MSGBOX Msg$                             ' Display explanation
     FOR I% = 1 TO 1000                      ' Start 2nd loop
          N% = INT(5000 * RND + 1)           ' Generate random number
          State% = DOEVENTS()                ' Yield to other events
     NEXT I%                                 ' Increment loop counter
     BEEP: BEEP                              ' Notify user 2nd loop is done
     MSGBOX "All Done!"                      ' Display final message
 END SUB
 
 SUB Form_Click ()
     CALL DoEventsDemo
 END SUB