Stepwise Refinement From the Inside out

1
Stepwise Refinement From the Inside out

• For larger programs, need to compile, run, and
  test the intermediate stages. Allows you to
  continually refine program so that it solves
  progressively more of your initial problem.
• Consider a program that reads in a file from the
  Census tables of populations and population
  densities and prints out a list of all the towns
  in the state.
• (For example, take a look at Maryland's
  geographic census data.)
• This is difficult, in part because towns' names
  are not always a single word, for example East
  New Market.

2
Basic Structure of the Program

• For now, lets assume a file "tempdata" contains
  the data. With this assumption, program becomes

3
Consider some simple data first

• Initially simplify problem by ignoring files
  header info, and look at only a single row of
  data

• Looking at 1st single row of data we see 7
  pieces of info to be read in (and ignored) before
  we come to the town name, in this case
  Aberdeen.

4
Refine to account for Compound Town Names

• Below works for towns like Aberdeen but fails
  for town names like Bel Air that are more than
  one

word. Need to keep reading in words, stopping
when we read in town or city or CDP or village
and saving the towns complete name.
5
Completed Program

• Allows the user to enter a filename
• Ignores header (which ends in NAME
• Loops thru file

6
ICE Finding the Highest Average

• You are given a list of midn names and alpha
  codes followed by a list of grades followed by a
  Print out the name of the student with the
  highest average. The format of your input is
  demonstrated in this example
• John Jeffery Jones m090101 85, 95, 22, 54
• Sandra Smith m090201 99, 98
• Xavier Xenon Jr m090400 78, 80, 82, 84, 86, 88,
  90
• For this input, your program would print out
  Sandra Smith had the highest average.
• Hint If S is an object of type string and c is
  an object of type char, then c S is the string
  object you get by tacking the character c onto
  the beginning of S.