Design Document for Lab Exercise #3

  Data objects and their attributes:

    Maximal exam score possible        constant  integer  MaxScore
    Minimal exam score possible        constant  integer  MinScore
    Number of exam scores in set       variable  integer  Number
    Total of all exam scores in set    variable  integer  Total
    Highest exam score in set          variable  integer  HighScore
    Lowest exam score in set           variable  integer  LowScore 
    Current exam score                 variable  integer  Score
    Average of all exam scores in set  variable  real     Average

  Algorithm:

    initialize Number and Total to zero
    initialize HighScore to MinScore
    initialize LowScore to MaxScore

    output directions for the user

    loop

      output prompt for next exam score
      input Score

      exit from loop when end of input stream is found

      if Score is valid

        increment Number by 1
        increment Total by Score

        if Score > HighScore

          HighScore = Score

        endif

        if Score < LowScore

          LowScore = Score

        endif

      else

        output message -- invalid exam score

      endif

    endloop

    if Number > 0

      calculate average = Total / Number (floating point calculations)

      output summary statistics for the user, including HighScore,
        LowScore, Number, and Average

    else

      output message -- empty set of exam scores

    endif