!-----  Ex7_4: Bubble Sorting   ---
   PROGRAM Ex7_4_Bubble_Method
      CHARACTER(LEN=15) :: word(100), wtemp
      INTEGER :: num, n, m
      DO num = 1, 100
         PRINT*, 'Input a word:'
         READ '(A)', wtemp;   IF( wtemp == "") EXIT
         WORD(num) = wtemp
      END DO
      num = num-1
      DO n = num, 2,-1
          DO m = 1, n-1
               IF( word(m) > word(m+1) ) THEN
                   wtemp = word(m)
                   word(m) = word(m+1)
                   word(m+1) = wtemp
               END IF
          END DO
      END DO
      DO n = 1, num
           PRINT*, word(n)
      END DO
   END PROGRAM Ex7_4_Bubble_Method