zdfsdf fdxgbfdcxgb fdxgbfdcgbfcd hgcfhngfvchvfghn fghngfcvhngvfhnvfgfgvhngvf

1. CS2006 - Data Structures I
Chapter 2
Principles of Programming
&
Software Engineering

2. 2
Topics
 Software Life Cycle
 Abstraction – Abstract Data Type
 OO Design
 Encapsulation
 Inheritance
 Polymorphism

3. 3
Introduction
 How do you write a Java program in COSC
1046/1047?
 Old fashion way
 Write code
 Compile
 Check syntax
 Run
 Check logic
 How about a large
project with a team?

4. 4
Introduction
 A better way
 Systematic way (Structured approach)
 Specify problem
 Analyze
 Design
 Implement
 Test
 Maintain

5. 5
Introduction
 SW Engineering:
 Computer science branch that provides
techniques for development of computer
programs
 Systematic approach to analyze, design,
implement, and maintain software
 Uses CASE tools (Computer Aided Software
Engineering)

6. 6
The Software Life Cycle
1. Specification
2. Design
3. Risk Analysis
4. Verification
5. Coding
6. Testing
7. Refining
8. Production
9. Maintainence

7. 7
1. Specification & Analysis
 Specification
 A contract between customers and
developers
 Not how, but about what
 May involve construction of a prototype
program to get more details from users.

8. 8
1. Specification & Analysis
 Example:
 “design and implement a software to store a
library’s catalogue of books”
 Input (partial):
 Librians enter new books as they arrive
 Library users enter search
keys to search through our list

9. 9
1. Specification & Analysis
 Process:
 Add new book
 Search for books
 Output:
 Show all the info about a book
 Requirements
 Are there any time/space/performance constraints

10. 10
2. Design
 Given:
 Clear & detailed specification of all aspects of
the problem
 Output:
 Design for a solution to the problem
(algorithm) - UML diagrams (about How)
 Idea:
 Use modular design
 Divide & conquer
 Divide the problem into smaller manageable parts.

11. 11
2. Design

12. 12
3. Risk Analysis
 Risks are primarily business related but
can be personal as well.
 Not an important issue for this course.

13. 13
4. Verification
 Determining the degree to which a software
product fulfills its specification
 Formal, theoretical methods for proving
algorithm correctness

14. 14
5. Implementation (Coding)
 Coding
 Translating the algorithm into a particular
programming language & removing syntax
errors
 Should not start unless previous stages are
well defined

15. 15
5. Implementation (Coding)
 Bottom-up implementation:
 First implement submodules, then modules
 Top-down implementation:
 Implement a module before implementing its
submodules A
S3
S2
S1

16. 16
6. Testing
 Careful design of test data is important
 Valid (In-range) data
 Invalid (out-of-range) data
 Random values of data
 Test several times on different
circumstances
 Any modification in the program needs re-
testing

17. 17
7. Refining the Solution
 Usually involves increasing the
"robustness" of a solution.
 Example: assume that the input will be
integers between 0 and 1000.
 During this step code would be inserted to actually
test the input values.

18. 18
8. Production
 Distribute the SW product to its intended
users
 Install the SW
 Use the SW

19. 19
9. Maintenance
 Correct errors not discovered during
testing
 Add more features
 Enhance existing features
 Modify to suit the user better

20. 20
Abstraction & Information Hiding
 Example: Cars brakes
Client
box
Car
Black box
Push
the brakes
My interior design is
using
Cylinder brakes
or
Drum brakes
Brake pedal pushed
Car stop

21. 21
Abstraction
 Abstraction separates the purpose of a
module from its implementation.
 Example: Sorting

22. 22
Abstraction
 Abstraction separates the purpose of a
module from its implementation.
 Example: Sorting
Client
box
Sort
Black box
Sort this data
please,
I don’t care
how you do it
I can sort data into
ascending order without
you knowing how
Unsorted data
Sorted data

23. 23
Procedural Abstraction
 Procedural Abstraction is the process of
separating the purpose of a method from
its implementation.
 Once written the method can be used without
any knowledge of how it is implemented - only
need to know the parameters.
 Example: ??

24. 24
Abstract Data Types
 ADT - a collection of data along with a set of
operations that can be performed on that
data.
 No details about how the data is stored or how
the operations on the data are implemented.
 An ADT is a general description of the design of
a module with no details.

25. 25
Abstract Data Types
 Examples
 Date class
 String class

26. 26
Abstract Data Types
 Data Structure - the implementation of an
ADT in a programming language.
 The details of data storage and how
operations are performed are crucial parts of a
data structure.

27. 27
ADT List
 Any List in general will allow the following
operations:
 Create an empty list
 Destroy a list
 Determine whether a list is empty
 Determine the number of items in a list
 Insert an item at a given position in the list
 What else?

28. 28
Object-Oriented Design
 Three elements to OOD:
 Encapsulation - combining data and
operations within one object.
 Inheritance - objects can inherit data and/or
methods from other objects.
 Polymorphism - objects can determine
operations at execution time.
 Every object knows its "true" type regardless of type
casting

29. 29
Object-Oriented Design
 Produce a collection of objects that have
behaviours
 How to do
 Identifying the objects in the problem
 UML
 Contents of Software Engineering (cosc 3506)

30. 30
Object-Oriented Design
 Consider the nouns and verbs in the
problem domain
Create a ATM machine which allow user to retrieve,
deposit, transfer and check balance of their accounts
ATM
Account: account
Open ()
Close()
Account
Type: String
Amount: double
transfer (int )
checkBalance()
retrieve
deposit ()

31. 31
Review
 The first phase of the life cycle of software
is the ______ phase.
 design
 risk analysis
 specification
 coding

32. 32
Review
 The syntax errors of a program are
removed during the ______ phase of the
program’s life cycle.
 verification
 coding
 testing
 refining
 maintenance

33. 33
Review
 Which of the following is an example of a
logical error?
 an algorithm that calculates the monthly
payment of a loan displays incorrect results
 an array subscript in a program goes out of
range
 a program expects a nonnegative number but
reads –23
 the beginning of a while loop is written as
“whille” instead of “while”

34. 34
Review
 During the design phase of the software
life cycle, the program is divided into
______.
 invariants
 loops
 Modules
 prototypes

35. 35
Review
 CASE tools refers
 Use Case for Applications
 Computer Aided Software Engineering
 Common Agent Software Engineering
 Contact Assistant Software Engineering

36. 36
Review
 A prototype program is created during the
______ phase of the software life cycle.
 design
 specification
 Coding
 testing

37. 37
Review
 Which of the following is not a goal of
Software Engineering:
(a) Make Complex Software/Systems Manageable.
(b) Create code implementations which are as big as
possible.
(c) Coordinate large number of developers.
(d) Handle complex software systems.

38. 38
Review
 A(n) ____ is a collection of data and a set
of operations on the data.
 method
 exception
 abstract data type
 data structure.

39. 39
Review
 With ______, objects can determine
appropriate operations at execution time.
 encapsulation
 inheritance
 Polymorphism
 information hiding.

40. 40
Review
 Object-oriented design identifies objects
by focusing on the ______ in the problem
statement.
 nouns
 verbs
 Adjectives
 adverbs