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' This example uses the UEVENT and ON UEVENT statements to enable user-
' defined event trapping. The SetUEvent routine signals a user-defined event
' and passes control to an event-handling routine. This example is a limited
' illustration of UEVENT statements, which are best suited for interfacing
' hardware to a computer.
 
' Note: To use this program or any user-defined event trapping, you must load
' the Quick library VBDOS.QLB with the /L option when you start Visual Basic.
 
' To try this example:
' 1. Choose New Project from the File menu
' 2. Copy the code example below to the code window
' 3. Press F5 to run the example
 
 CLS                             ' Clear the screen
 PRINT "This program asks for 10 numbers between 0 and 9, inclusive."
 PRINT "As each number is input, it is evaluated to determine whether"
 PRINT "it is odd or even. Odd numbers cause a user-defined event"
 PRINT "to occur. Even numbers do not.": PRINT
 ON UEVENT GOSUB Event1
 UEVENT ON
 DO
     PRINT "Enter a number --> ";
     N = VAL(INPUT$(1)): PRINT N: PRINT
     SELECT CASE N
          CASE 1, 3, 5, 7, 9
               PRINT "An odd number was input causing a user-defined event.";
     CALL SetUEvent
          CASE ELSE
               PRINT "No user-defined event occurred.": PRINT
    END SELECT
    LoopCount = LoopCount + 1
 LOOP UNTIL LoopCount = 10
 END
 
Event1:
     PRINT "Now processing the UEVENT. The odd number was"; N
     PRINT
     RETURN