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Visual Basic Introduction

IDS 306

from Shelly, Cashman & RepedeMicrosoft Visual Basic 5: Complete

Concepts and Techniques

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Processing

Parallel Processing -- more than one CPU

(each with its own memory); able to carry

out more than one instruction at a time

Multitasking -- one processor, moves back

and forth between programs

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Graphical User Interface (GUI)

Design Should be under users control

user should be able to customize

Form should follow function Use concepts and metaphors familiar to

user; parallel real-world experience

Visually and functionally consistent Immediate feedback

Attempt to prevent user mistakes

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Program Development Life Cycle

(PDLC)Methodology -- organized plan that breaks

process into steps

Analyze the problem

Design the problem

Code the program

Test and debug program

Formalize solution

Maintain the program

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Hierarchical Input Process

Output (HIPO) Chart A.k.a. hierarchy chart ortop-down chart

Represents subdivision of activities visually

Lowest level instruction -- procedure

p. I.7p. I.7

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Flow Chart Process Symbol

Input/Output (I/O)

Flowline Annotation

Decision

Terminal

Connector

Predefined Process

p. I.7p. I.7

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Major Constructs of Structured

Programming Control Structures

Sequence

Selection

Case

Repetition

DoWhile DoUntil

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Control Structures Sequence Control Structure -- used to show a

single action or one action followed in order

(sequentially by another) Selection Control Structure -- used to tell the

program which action to take based on a certain

condition Case Control Structure -- form of selection

that allows for more than two alternatives

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Control Structures (cont.) Repetition Control Structure -- a.k.a. looping

oriteration; used when a set of actions is

performed repeatedlyDo...While loop repeats as long as condition is true

(may never execute)

Do...Until loop evaluates condition at end of theloop (will always execute at least once)

Nested Control Structure -- contained within

other control structures

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Object-Oriented Programming

(OOP) Object -- anything real or abstract, about

which you store both data and operations

that manipulate the data

Class -- an implementation that can be used

to create multiple objects with the same

attributes and behavior

Object is and Instance of a Class

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Generalization Hierarchy

Object-oriented design tool used to show the

relationships among classes of objects

p. I.11p. I.11

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Object-Oriented Terms Attribute -- identifying characteristics of

individual objects, such as name or color

Operation -- an activity that reads ormanipulates the data of an object; called

service in OOD, in OOP called a method

Message -- has two parts: name of object towhich message is sent, name of operation that

will be performed. In OOP called event

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Object Structure Diagram

p. I.12p. I.12

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Event Diagram

Used to represent relationships among events andoperations

Operations shown in rounded rectangles

Events shown on lines with arrows

p. I.13p. I.13

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Major Constructs of OOP

Encapsulation

Inheritance

Polymorphism

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Encapsulation

Capability of an object to have data

(properties) and functionality (methods)

available to the user without the user having

to understand the implementation within the

object

Also called information hiding

Process of hiding the implementation details

of an object from its user

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Inheritance A descendent class (subclass) that differs

from its superclass in only one way contains

just the code or data necessary to explain

the difference

Also known as subclassing

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Polymorphism

Allows an instruction to be given to an

object in a generalized rather than specific

detailed command

Same command will get different but

predictable results depending on object

receiving command Specific actions, internal to object differ,

results are the same

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Rapid Application Development

(RAD) Use of prebuilt objects to make program

development much faster

Shorter development life cycles

Easier maintenance

Capability to reuse components

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Benefits of OOP

Reusability -- classes designed to be reused in

many systems or create modified classes using

inheritance Stability -- classes designed for repeated reuse,

become stable over time

Easier Design -- object is a black box Faster Design -- can be created from existing

components

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Prototyping

Process where developers iterate between

refining the specifications and building

working models of the system

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Visual Basic Properties -- attributes of objects

Controls -- check boxes, list boxes, etc.

Forms -- windows that contain applications

controls

Events -- messages or requests for service

Procedures -- operations or services

include methods, functions, subroutines

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Creating VB Applications Create the interface

Set the properties

Write the code