Before:

class event
{
   public:
      // Mutators
      bool setStartTime( short hour, short min, short sec );
      bool setEndTime( short hour, short min, short sec );
      bool setDuration( int duration );

      // Selectors
      int getDuration()
      { 
         durationMinutes = end_time - start_time; 
         return durationMinutes; 
      }

   private:
      time start_time;   // Start time
      time end_time;     // End time
      int durationMinutes;
};