An Introduction to Visual Basic.NET Chapter Microsoft Visual Basic.NET: Reloaded 1

An Introduction to Visual Basic .NET

Chapter Microsoft Visual Basic .NET: Reloaded

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2Microsoft Visual Basic .NET: Reloaded

Objectives

• Explain the history of programming languages

• Define the terminology used in object-oriented programming languages

• Create a Visual Basic .NET Windows-based application

• Manage the windows in the IDE

• Set the properties of an object


Objectives (continued)

• Add a control to a form

• Use the Label and Button tools

• Enter code in the Code Editor window

• Save a solution

• Start and end an application


Objectives (continued)

• Print a project’s code

• Close a solution

• Open an existing solution


Programmers

• Programmers

• People who write programs

• Programs

• Directions given to a computer accomplish a given task


A Brief History of Programming Languages

• Machine Languages• 0 (for on switch)

• 1 (for off switch)

• Tedious and prone to error

• Assembly Languages• More advanced than machine languages

• Mnemonics (memory aids)

• Examples: MUL b1, ax

• Require an assembler


A Brief History of Programming Languages (continued)

• High Level Languages• Require Interpreter or compiler

• Interpreter translates high-level into machine code line-by-line while program is running

• Compiler translates entire program before program has run

• English like syntax

• Allow for object-oriented programming• Programmer focuses on using objects to achieve

the program’s goal


OOP Terminology

• Object

• Anything that can be seen touched, or used

• Has Attributes - also called Properties

• Characteristics that describe the object

• Has Behaviors - also called Methods

• Operations the object is capable of performing

• Class

• Pattern or blueprint used to create an object


OOP Terminology (continued)

• Encapsulation• Combination of attributes and behaviors that

describe object created by class

• Abstraction• Hiding internal details of object from user

• Inheritance• Ability to create one class from another

• Polymorphism• Same instruction carried out differently

depending on the object giving the instruction


Illustration of OOP Terms


Visual Studio .NET

• IDE

• Integrated Development Environment

• Contains all the features needed to create, run, and test programs

• Editor for entering program instructions

• Compiler for running and testing program

• Allows creation of Web-based and Windows-based applications


Visual Studio .NET (continued)

• Solution .sln

• Container for project and files for application

• Project .vbproj

• Container for storing files associated with a specific piece of the application

• Files

• Individual files necessary to store information about the application

• Include forms and class information


Illustration of solution, project, and file


Starting Microsoft Visual Studio .NET


Visual Studio .NET 2003 startup screen


Purpose of windows in the IDE


HOW TO…


Creating A Visual Basic .Net Windows-Based Application


Creating A Visual Basic .Net Windows-Based Application (continued)


HOW TO…


The Dynamic Help Window


The Windows Form Designer Window• Windows form object (form)

• Foundation for the user interface


Solution Explorer Window

• Contains: • Projects

• References• Addresses of memory cells

• Namespace – block of internal memory cells• Contains code that defines a group of related

classes

• Source files• Contains program instructions – called code• Examples: Assembly information, Forms


The Solution Explorer Window (continued)


The Properties Window• Object box (contains name of selected object)

• Properties list has 2 columns• Left column displays property names• Right column displays Settings box

• Contains current value for each property


Properties of a Windows Form Object• Select object to display properties

• Dot member access operator• Separates words in property name

• Example: System.Windows.Form.Form


Properties of a Windows Form Object (continued)


The Toolbox Window• Toolbox contains tools and other components

used in creating application• Tools are called controls• Controls are displayed on the form


HOW TO…


The Label Tool• Use tool to instantiate a Label object

• Object displays text that user is not allowed to edit


HOW TO…


The Button Tool• Button Tool instantiates a Button control

• Button Control used to perform immediate action when clicked


HOW TO…


The Code Editor Window

• Events

• Actions such as clicking, double-clicking, and scrolling

• Event Procedures

• Set of Visual Basic instructions (code)

• Tells an object how to respond to an event

• Contained in the Code Editor Window


HOW TO…


The Code Editor Window (continued)



• Class Definition• Block of code that specifies attributes and

behaviors of an object

• Inherits keyword• Inherits System.Windows.Forms.Form

• Allows derived class to inherit attributes and behaviors of base class

• Windows Form Designer generated code section• Contains code generated by the designer




Code Editor Window (continued)

• Class name list box

• Lists names of objects on user interface

• Method name list box

• Lists events selected object responds to

• Procedure

• Block of code that responds to an event




Code Keyword Examples

• Public class frmCommission• Public indicates class can be used by code

defined outside the class

• Private Sub btnExit_Click…• Sub is abbreviation for sub procedure

• Block of code that performs a specific task

• Private indicates procedure can be used only in class in which defined

• btnExit is name of object on user interface

• _Click is name of the event (Click)


The Me.Close Method

• Instructs computer to terminate current application

• Me refers to the current form

• .Close refers to an intrinsic method

• Part of built-in VB .NET language

• Code is performed using sequential processing, also known as sequence structure


The Me.Close Method (continued)


Saving a Solution


Starting and Ending an Application


Setting the startup object


HOW TO…


Starting an Application


Printing Your Code


Closing the Current Solution


Opening an Existing Solution


Programming Example – State Capitals

• Application displays the capital of the state in a label when a button with the state’s name is clicked

• Create buttons with labels for the following states : Alabama, Alaska, Arizona, and Arkansas

• Create an exit button to close the application


User Interface


Objects, Properties, and Settings


Code


Summary

• Programming languages have evolved from machine languages to high-level program languages

• Object Oriented Programming includes:

• Objects – things with attributes and behaviors

• Attributes are the characteristics of an object

• Behaviors are actions that an object performs

• Integrated Development Environment (IDE)

• Used to manage windows, set properties, and write code for an application


Summary (continued)• Forms are the user interface of an application

• Contain controls such as Buttons and Labels• Have code to perform specific tasks

• Code contained in Code Editor Window

• Additional Tips:• Saving your Solution (do often)

• Saves all files associated with the application• When starting an application

• You must specify a startup form• Print your code

• For ease of understanding and future reference

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An Introduction to Visual Basic.NET Chapter Microsoft Visual Basic.NET: Reloaded 1