Modules, Hierarchy Charts, and Documentation

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Modules, Hierarchy Charts, and Documentation
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• Programming Logic and Design, Second Edition,
  Comprehensive

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Objectives

• After studying Chapter 3, you should be able to
• Describe the advantages of modularization
• Modularize a program
• Understand how a module can call another module
• Explain how to declare variables

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Objectives

• After studying Chapter 3, you should be able to
• Create hierarchy charts
• Understand documentation
• Create print charts
• Interpret file descriptions
• Understand the attributes of complete
  documentation

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Modules

• Large programs are never written as one huge
  series of steps.
• Programs are broken down into units called
  modules.
• Modules are also referred to as
• subroutines
• functions
• procedures
• methods

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AdvantagesModularization AllowsMultiple
Programmers to Work on a Problem

• Dissect large task into modules
• divide the task among various people

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Modularization Allows You to Reuse Your Work

• REUSE YOUR WORK
• You can find many real-world examples of
  reusability

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Modularization
Makes It Easier to Identify Structures

• When you combine several programming tasks into
  modules, it may be easier for you to identify
  structures

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Selection of Logic From a Payroll Program
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Modularized Logic from a Payroll Program

• The single program segment shown in Figure 3-2
  accomplishes the same steps as the two program
  segments shown together in Figure 3-3 both
  programs are structured

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Another Example

• Modules can better help you determine if your
  flowchart is structured.

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Modularizing a Program- Flowchart Symbols

• Sentinel Symbols
• A module has it own sentinel symbols (Start and
  End)
• The Start symbol has the name of the module
• The End symbol has the word RETURN

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Modularize a ProgramNaming the MODULE

• In this text, module names will follow the same
  two rules used for variable names
• Module names must be one word
• Module names should have some meaning
• Additionally, in this text module names will be
  followed by a set of parentheses

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Another Example
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Lets try

• Example 1 -
• Write a flowchart showing the logic to calculate
  the volume of an undetermined amount of rooms.
  (Volume Length Width Height)
• Think about what your logic needs -
• Input
• Processing (for more than one room)
• Output
• Create a flowchart first without and then with a
  module.

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Example 1 - Without a module
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Example 1 - With a Module
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Example 2

• Create a flowchart showing the logic needed to
  accept a series of numbers, print each number
  when it is read, and print the total after all
  the numbers are read.
• An example run 28
• of the program 10
• 15
• 53

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Example 2 - Without a Module
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Example 2 - With a Module
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Modules Calling Other Modules

• A module can be called by both the main program
  or by another module
• Modules called by other modules are called
  submodules.

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Averaging Program with Submodules
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Flowchart and Pseudocode for Averaging Program
with Modules
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Flowchart for Averaging Program with Submodules
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Another ToolCreating Hierarchy Charts

• You can use a hierarchy chart to illustrate
  modules relationships
• A hierarchy chart does not tell you what tasks
  are to be performed within a module it does not
  tell you when or how a module executes
• The hierarchy chart for the last version of the
  value-averaging program looks like Figure 3-7

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Hierarchy Chart for Value-Averaging Program
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An Organizational Hierarchy Chart
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Declaring Variables

• Declaring a variable provides a name for a memory
  location
• where computer stores variable values
• notifies computer of data type
• Programming languages declare variables
  differently, but minimally you must
• give the variable a name
• give the variable a data type

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Declaring Variables

• An annotation symbol or annotation box is simply
  an attached box containing notes
• You can use an annotation symbol any time you
  have more to write than conveniently fits within
  a flowchart symbol
• Programmers sometimes create a data dictionary,
  which is a list of every variable name used in a
  program, along with its type, size, and
  description
• When a data dictionary is created, it becomes
  part of the program documentation

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Declaring Variables in a Flowchart

• One of first things done in a program in
  declaring variables

• Next to the process symbol Declare Variables is
  an annotation box stating the names and types of
  the variables
• Annotation boxes can be used anytime text does
  not fit in a symbol

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Declaring Variables

• Languages including COBOL, C, C, Java, and
  Pascal require declaration of variables with name
  and type
• Modern programming languages variables are
  declared within each module that uses them. Such
  variables are known as local variables
• We will use global variablesvariables that are
  given a type and name once- used in all modules
  of the program

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What is Documentation

• All supporting material that goes along with a
  program
• User documentation
• Manuals
• Training material
• Program documentation
• used for planning or modifying programs
• internal and external program documentation

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PROGRAM Input Documentation

• A file description describes the data contained
  in an input file
• Files description as part of an organizations
  information systems documentation

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Input The inventory file description in Figure
3-20 shows that each items name occupies the
first 15 characters of each record in the file

• The price of any item in the inventory file is
  allowed five positions, 16 through 20
• Two of the positions are reserved for decimal
  places
• Typically, decimal points themselves are not
  stored in data files they are implied or assumed

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Input Documentation

• Numeric data are stored with leading zeros
• Programmers create one variable for each field in
  the input file

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Input Documentation

• Recall the data hierarchy relationship introduced
  in Chapter 1
• Database
• File
• Record
• Field
• Character

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Input Documentation

• The programmer needs to know is
• What is the name of the file?
• What data does it contain?
• How much room does the file and each of its
  fields take up?
• What type of data is each fieldcharacter or
  numeric?

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Expanded Inventory File Description

• The file description in Figure 3-21 contains nine
  fields

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Internal Documentation

• //
• / Program Payroll /
• / Author Dan Dainton /
• / Date March 2, 1999 /
• //

• Comments within programming code
• Lines of code that do not effect the running of
  the program.
• Written so programmers can
• understand what the program is doing
• why the program is doing it

// / This module
calculates/ / tax deductions for / /
payroll checks. / /
/
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External Documentation

• All supporting paperwork a programmer develops
  before writing a program.
• External documentation can describe
• Input
• Processing
• Output
• Output documentation is developed first. Why?

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Output Documentation

• Generally, the reason you would write a program
  in a business environment is because particular
  information is needed.
• Can the programmer decide what information is
  needed and how its designed? Can the user
  requesting the information?

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Output DocumentationDesigning a Report

• Printed reports are the most common type of
  output.
• Reports are designed on printer spacing charts.
• Looks like a grid
• One character per box

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A Report Design Example

• This report will track inventory for a company
• Report Title ie Inventory Report

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Creating Column Headings

• Report column heading
• constant that appear on every page of the report
• Because the headings remain the same throughout
  the report, they are written on the print chart
  literally.

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More on Detail Lines

• Detail lines
• have variable data
• probably have a variable amount of detail lines
  on the report
• All the detail lines look the same, but you need
  to show 2 - 3 lines in your print chart. Why?

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Understanding Documentation

• Documentation refers to all of the supporting
  material that goes with a program
• Two broad categories of documentation are
  intended for the programmer and for the user
• People who use computer programs are called end
  users, or users for short
• When programmers begin to plan the logic of a
  computer program, they require instructions known
  as program documentation

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Understanding Documentation

• Program documentation falls into two categories
  internal and external
• Internal program documentation consists of
  program comments, or nonexecuting statements that
  programmers place within their code to explain
  program statements in English
• External program documentation includes all the
  supporting paperwork that programmers develop
  before they write a program

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Output Documentation

• Output documentation is usually the first to be
  written
• The most common type of output is a printed
  report
• You can design a printed report on a printer
  spacing chart, which is also referred to as a
  print chart or a print layout
• The title and column headings will be constant on
  every page of the report so they are written on
  the print chart literally

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Printer Spacing Chart
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Printer Spacing Chart with First Title
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Printer Spacing Chart with Title and Column
Headings
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Output Documentation

• The exact spacing and use of upper- or lowercase
  make a difference
• Notice that the constants used within a report do
  not need to follow the same rules as variable
  names
• A print layout typically shows how the variable
  data will appear on the report
• Each line with its Xs and 9s representing data is
  a detail line because it contains the data details

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Print Chart with Generic Data
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Variable Data in Report Heading
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Heading with Page Numbers
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Print Chart with Literal in Each Detail Line
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Output Documentation

• Detail lines typically appear many times per
  page, as opposed to heading lines, which usually
  appear only once per page
• Besides header lines and detail lines, reports
  often include special lines at the end of a
  report
• Even though lines at the end of a report dont
  always contain numeric totals, they are usually
  referred to generically as total lines

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Report with Variable Data at End
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Report with Constant Data at End
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Report with Combined Constant and Variable Data
at End
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Completing the Documentation

• Program Documentation
• Design outputPlan the logic of the program
• Code the program
• Test the program
• User documentation
• User documentation instructional materials
  that nontechnical people use

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Completing the Documentation

• The areas addressed in user documentation may
  include
• Description of input for the program
• Who needs the output
• What output should look like
• How to interpret and react to any error message
  generated by the program
• How frequently the program needs to run

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IN Summary- Review Modules

• Programming using modules
• Module is given a name- that name is CALLED by
  the calling program
• A module can call other modules

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Summary- Variables

• To Declaring a Variable providing a name for
  the memory location where the value is stored
• Identify the data type You can use a hierarchy
  chart to illustrate modules relationships
• Documentation refers to all of the supporting
  material that goes with a program
• Output documentation is usually written first

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Summary- Documentation

• File description lists the data in a file (
  description, size, and data type)
• Program documentation file descriptions,
  printer spacing charts etc
• User Documentation manuals or other
  instructional materials that nontechnical people
  use as well as the operating instructions that
  computer operators and data-entry personnel may
  need