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

After studying this chapter, you should be able to Understand problemsolving concepts, formulate algorithms using pseudocode, realize the complexity writing algorithms, understand an eventdriven environment, describe how classes and objects work, use and understand the terminology of the object paradigm.

Oriented Paradigm

• 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.

and nonvisual software components.

• Begin understanding the relationship of

Visual Basic NET to the event-driven and object paradigms.

– Find the largest number in the set of numbers.

• Describing Your Solution

– Solve the problem yourself.

– Formulate your solution approach.

style used to document the solution to a

program.

• Algorithm is the formal term for the set of

steps used to solve a problem.

1.1 Problem Solving (cont.)

• 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

– 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

1.1 Problem Solving (cont.)

• 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

– 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.

Solving 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.

– 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

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

– 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

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

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

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

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

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

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

• 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.