! 例題 6-1  成績のソート（置換え法） ［配列の基本 ］
PROGRAM ex6_1

  IMPLICIT NONE
  INTEGER :: m, mark( 1 : 100 ), n = 0, max, maxi, i, j

  DO WHILE ( n <= 99 )
    PRINT *, 'Input mark, or negative one to stop: '
    READ *, m
    IF ( m < 0 ) EXIT
    n = n + 1
    mark( n ) = m
  END DO

! sorting
  DO i = 1, n - 1
    max = mark( i )
    maxi = i
    DO j = i + 1, n
      IF ( mark( j ) > max ) THEN
        max = mark( j )
        maxi = j
      END IF
    END DO
    IF ( maxi /= i ) THEN
      mark( maxi ) = mark( i )
      mark( i ) = max
    END IF
  END DO

! output
  DO i = 1, n
    PRINT '( 1X, "rank", I3, " = ", I10 )', i, mark( i )
  END DO

END PROGRAM ex6_1