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Software Fundamentals:

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Title: Software Fundamentals:

1
Software Fundamentals

Programs and Programming
Software

2
Programming Definitions

Programs
traditional programs
macros, batch files
Programming Languages
Programming
Program design
Coding
Debugging
Documentation
Maintenance
Programmers
Programming Environments

3
Programming Languages

Commonalities
All have a syntax
All have the same basic operations
Input, Output
Processing
math, text
Control operations
if statements
loops (ability to repeat instructions)

4
Language Differences

Purpose
COBOL, FORTRAN, SNOBOL, LISP
Power - two meanings
degree of control over machine
how much is accomplished by each statement
Safety
Portability
Maintainability
Readability/Modularity/Reuse

5
History of Languages

Gen 1 and 2 not important for you
Gen 1 Machine Language
All statements 0s,1s
Gen 2 Assembly Language
0s,1s replaced w/ short codes
Gen 3 Higher Level Languages
each statement several low level statements
Gen 4 4GLs
each statement a program in 3GL
Emphasis on what not how

6
Example of a 3 GL Program

Dim miles, fuel, mileage
Input enter the miles traveled, miles
Input enter the gallons of gas used, fuel
Let mileage miles/fuel
Lprint Miles Miles
Lprint Gas Used fuel
Lprint Mileage Milage
End

7
Example of a 4GL (SPSS)

Type in a command directly and execute it
FREQUENCIES VARIABLESpaysat growsat
/STATISTICSSTDDEV VARIANCE RANGE MEAN
Use a dialog box to specify what to do

Generates the same command above
8
History of Programming

Customized software
programming is an art, spaghetti code
Structured programming
modules, documentation, COBOL
Programmer Tools
code generators
reverse engineering
programming environments
Packaged software
Packaged objects/modules

9
Modular Programming

Main.
Perform Input-Wage-Hours.
Perform Calculate-Pay.
Perform Display-Pay.
Stop Run.
Input-Wage-Hours.
Display What is the wage?
Accept Wage.
Display enter hours
Accept Hours.
Calculate-Pay.

Statement that calls module
Module Name
The next module
10
Object-Oriented Software

A new way to look at programming

11
Object-Oriented Paradigm

OO is a way of viewing the world
we tend to group items (objects) into categories
(classes)
the objects in each category have similar
properties
behavior
OO is a way of recording reality
used to capture user requirements
OO is a way of programming

12
OO Concepts

A class is ...
A collection of similar objects
The set of all .
A definition
Properties, behaviors they share
An Instance of a Class
a single object in the class
A sub-class
subset of objects in parent class
used whenever not all objects in the class are
exactly the same
A message
when one object talks to another

13
Bank Accounts Object Class

Properties
Customer ID
Balance
Methods
Deposit/Withdraw
Print Statement
Chg Address

Checking Accounts Object Class
Savings Accounts Object Class

Properties
Free checks
Min Balance
Methods
Print Statement
Chg Address

Properties
Interest rate
Methods
Calculate Interest
Print Statement
Change Address

Messages
14
OO Example for Bank

Object Class Accounts
The set of all accounts
All accounts have these properties
ID number
Balance
All accounts have these methods (behaviors)
Deposit, Withdraw (transactional)
Print Statement (output)
Change Address (chg property)
Instance of the Accounts class
555-111, 2000.00 (ID , Balance amount)
Sub-classes of the Accounts Class
Savings Accounts Checking Accounts
Messages
Account class might receive a message from
Customer instance (create an account for me)
Account instance might send a message to
Collections Officers class (this account is
overdrawn)
Printer instance (print this statement)

15
Benefits of OO Programming

Has both standardization and flexibility
Inheritance gives stability
A sub-class inherits everything from parent
Both properties and methods
Customization gives flexibility
Unless method is private
you can change it make it behave differently
Unless a property is private
you can drop it, change its format, size, etc.
You can add new methods and properties

16
Examples of Object Statements

Excel
Worksheets.Add
Worksheet(1).Caption January
Worksheet(January).Activate
Word
Selection.Font.Color wdColorRed
Powerpoint
ActivePresentation.SlideShowSettings.Run
ActiveWindow.ViewType ppViewSlideSorter

17
OO Programming Languages

Statements in an OO language help
create classes
define properties (like fields in a record)
define methods (behaviors)
keep track of instances of a class (objects)
create sub-classes
When you use an OO program it might
create instances
initiate methods
change properties
send messages

18
OO Programming Environments

Programming Environment
software used to write programs
programming support tools
libraries of object class definitions
diagramming tools to show
class relationships
parent, sub
Message interactions
What objects talk to other objects

19
Object Thinking Project

Scenario
Company owns a chain of ski shops and they need a
system to keep track of products and supplies on
hand. The system should allow the ski shop
managers to
Create new products or supplies, Place orders,
etc
Your Tasks
Develop a hierarchy of classes for the system
that has at least one super-class and two
subclasses
For each class of objects specify
some properties it might have
some methods it might have
Also, give me an example of a possible instance