! 例題 7-4  単語の並べ替え（バブル・ソート）［文字列の大小比較 ］
PROGRAM ex7_4

  IMPLICIT NONE
  INTEGER :: num, n, m
  CHARACTER ( LEN = 15 ) :: word( 1 : 100 ), wtemp

  DO num = 1, 100
    PRINT *, 'Input a word in the lower-case letters, &
                                   &or empty to stop:'
    READ '( A )', wtemp
    IF ( wtemp == '' ) EXIT
    word( num ) = wtemp
  END DO
  num = num - 1                              ! 総語数

  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 '( 1X, A )', word( n )
  END DO

END PROGRAM ex7_4