Lecture Learning programming using Visual Basic Net – Chapter 1 Problem solving and the objectoriented paradigm

CHAPTER ONE
Problem Solving and the ObjectOriented Paradigm


Objectives
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•
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1- 2

Understand problem-solving concepts.
Formulate algorithms using pseudocode.
Realize the complexity writing algorithms.
Understand an event-driven environment.
Describe how classes and objects work.
Use and understand the terminology of the
object paradigm.
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Objectives (cont.)

1- 3

• Demonstrate the difference between visual
and nonvisual software components.
• Begin understanding the relationship of
Visual Basic .NET to the event-driven and
object paradigms.

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1.1 Problem Solving

1- 4

• Use computer software to help solve
problems.
– Sample Problem
• Problem Description
– Find the largest number in the set of numbers.

• Describing Your Solution
– Solve the problem yourself.
– Formulate your solution approach.
– Translate your solution.

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1.1 Problem Solving (cont.)

1- 5

• Pseudocode (false code) is an outline
style used to document the solution to a
program.
• Algorithm is the formal term for the set of
steps used to solve a problem.

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1.1 Problem Solving (cont.)

1- 6

• Algorithms
– A set of ordered steps for solving a problem,
such as a mathematical formula or the
instructions in a program. The terms algorithm
and logic are synonymous. Both refer to a
sequence of steps to solve a problem. Taken
from TechEncyclopedia.com.

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1.1 Problem Solving (cont.)

1- 7

• Algorithms (cont.)
– A formula or set of steps for solving a
particular problem. To be an algorithm, a set
of rules must be unambiguous and have a
clear stopping point. Algorithms can be
expressed in any language, from natural
languages like English or French to
programming languages like Visual Basic.

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1.1 Problem Solving (cont.)

1- 8

• Getting Data and Displaying Results
– Most algorithms need data.
– You must be able to display the results of an
algorithm.
– Input data must be accurate.
– Algorithm results range from simple to
complex.

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1.1 Problem Solving (cont.)

1- 9

• Getting Data and Displaying Results (cont.)
– Major Tasks of a Computer-Base Solution
• Write appropriate computer code to accept and
validate data.
• Write appropriate computer code to implement the
algorithm.
• Write appropriate code to format the results.

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1.2 The Event-Driven ProblemSolving Environment
• Most of today’s computer applications are
event driven.
• Helps developer organize a solution into
small segments of code.
• One organizes a solution around a series
of events.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving
• Classes and Objects
– Payroll System problem.
– Procedural programming has separate data
and program logic.
– Object-oriented programming (OOP)
combines the data and program logic.
– Methods describe the behavior associated
with an object.
– Encapsulates means an object holds in its
capsule both data and behavior.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving (cont.)
– A class is a definition or template that defines
how objects are created.
– An instance of a class is another name for an
object.
– Special methods known as classes methods
may be accessed by a class.
– Each object instantiated from a class has
identical data elements and methods.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving (cont.)
• Class Hierarchies
– The “is a” relationship may be used describe
class hierarchies.

– A UML (Unified Modeling Language) class
diagram may be used to define classes.
– A subclass descends from a superclass or
base class.
– A superclass contains data and behavior
common to subclasses.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving (cont.)
• Inheritance means a subclass acquires all
data elements and behaviors of its related
superclasses.
• Member describes the contents of a class.
• Siblings describe any two or more classes
that descend from the same superclass.
• An abstract class provides a base class
but cannot be used to instantiate objects.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving (cont.)
• Benefits of Using Object Orientation in
Problem Solving
– Reflects the natural way we think.
– The same class definition can be used in
many applications.
• Supports the concept of code reuse.

– In creating a subclass, we automatically
inherit all members from the superclass.
– Polymorphism enables the same method to
assume different behavior.
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1.3 Using the Object-Oriented
Paradigm in Problem Solving (cont.)
• Visual versus Nonvisual Components
– Some objects can be seen on the GUI.
– Other objects cannot be seen on the GUI.
– Microsoft provides both visual and nonvisual
components with Visual Basic .NET.

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1.4 Object Paradigm in Visual
Basic .NET
• Supports both the procedural and objectoriented paradigms.
• Supports both visual and nonvisual
classes.
• Fully supports inheritance and
polymorphism.
• A namespace identifies a set of classes
that are treated as a group.
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Chapter Summary
• Problem solving with a computer requires the
developer to first solve the problem without a
computer.

• Writing algorithms may be difficult.
• Most computer applications also include code to
obtain input data and to display results.
• An event-driven environment is an application
which responds to events generated by the user
or by the system.
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Chapter Summary (cont.)
• In an event-driven environment, code is
organized into small units called event
procedures.
• Objects are software components created
from a template called a class.
• Each class template defines data and
behaviors that each object created from
the class possesses.
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Chapter Summary (cont.)
• Classes can be arranged in hierarchies
that define a set of “is a” relationship.
• Superclasses (or base classes) are at the
top of the hierarchy and subclasses
descend from superclasses.
• A subclass “is a” superclass.
• The object paradigm and polymorphism
provide a very natural and flexible
environment.
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Chapter Summary (cont.)
• Classes can define visual or nonvisual
objects.
• Most classes created to solve business
problems are nonvisual.
• Visual Basic .NET creates event-driven
solutions that use a combination of the
object and nonprocedural paradigms.

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