Detailed Design Representations Chapter 9 of Code Complete

1
Detailed Design Representations (Chapter 9 of
Code Complete)

• Steve Chenoweth
• CSSE 375, Rose-Hulman
• Based on Don Bagerts 2006 Lecture

2
Today (Mon, Sep 17, 2007)

• Review Reuse Reusability
• Two topics
• Detailed design pseudocode this
• Maintenance Management Organization
• Tonight Turn in your teams maintenance plan
• Note Exam, Wed night, Oct 3, 7 9 PM

3
Outline

• Detailed Design Representations
• Background
• Pseudocode
• Other Representations

4
Background

• In some ways, detailed design is becoming a lost
  art
• Nowadays, programmers often write source code
  directly from high-level design
• Is this a good thing?

5
What is Pseudocode?

• An informal, natural-language notation for
  describing an algorithm
• Advantages
• Structure is similar to source code
• Can describe various levels of detail

6
Example Whether or not an integer is a prime
number 1/3

• First iteration (keeps to definition of prime
  number)
• If the integer lt 2
• Return false
• Else
• Determine whether there is a factor between 2
  and the
• integer minus 1
• If no factor is found
• Return true
• Else
• Return false
• End If
• End If

7
Example Whether or not an integer is a prime
number 2/3

• Second iteration (Takes advantage of known
  facts)
• If the integer lt 2
• Return false
• Else if the integer 2
• Return true
• Else if the integer is even
• Return false
• Else
• Determine whether there is a factor between 3
  and the square
• root of the integer
• If no factor is found
• Return true
• Else
• Return false
• End If
• End If

8
Example Whether or not an integer is a prime
number 3/3

• Third iteration (Determination loop and variables
  included)
• If n lt 2
• Return false
• Else If n 2
• Return true
• Else If n is even
• Return false
• Else
• FactorNotFound true
• Index 3
• While FactorNotFound and Index lt the square
  root of n do
• If Index is a factor of n
• FactorNotFound false
• Else
• Index Index 2
• End if
• End While

9
Group Discussion Do you think that pseudocode is
useful?
10
Other Detailed Design Representations

• Flowcharts
• Classic
• Examples
• http//www.tpub.com/neets/book22/93c.htm
• http//www.fh-jena.de/kleine/history/software/IBM
  -FlowchartingTechniques-GC20-8152-1.pdf (from
  1969!)
• Structured
• Example
• http//www.cs.umd.edu/hcil/members/bshneiderman/ns
  d
• Control Structure Diagrams
• jGRASP http//www.jgrasp.org/

11
jGRASP Exercise(if we have time)