Chapter 1
Introduction to Visual
Basic .NET 2008
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Chapter Objectives (1 of 2)
• Describe the process of visual program design
and development.
• Explain the term object-oriented programming.
• Explain the concepts of classes, objects,
properties, methods, and events.
• List and describe the three steps for writing a
Visual Basic project.
• Describe the various files that make up a
Visual Basic project.
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Chapter Objectives (2 of 2)
• Identify the elements in the Visual Studio
environment.
• Define design time, run time, and debug time.
• Write, run, save, print, and modify your first Visual
Basic project.
• Identify syntax errors, run-time errors, and logic
errors.
• Use Auto Correct to correct syntax errors.
• Look up Visual Basic topics in Help.
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1
Writing Windows Applications with VB
(1 of 2)
• Windows Graphical User (GUI) Interface
– Defines how elements look and function
Text boxes
Check box
Radio buttons
Message box
Buttons
Picture box
Label
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Writing Windows Applications with VB
(2 of 2)
Windows are called forms.
Elements are called
controls and are added
using a toolbox.
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Programming Languages—Procedural,
Event Driven, and Object Oriented
•
Procedural—Cobol, Fortran, Basic
•
Event-Driven Programming(VB 6.0 and previous)
• Program specifies exact sequence of all operations.
• Contain some elements of object-oriented programming, but not
all
•
Object-Oriented Programming (OOP) (VB .NET)
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• User controls sequence
– Click event
– Double Click event
– Change event
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2
The Object Model (1 of 2)
In VB, you will work with objects that have
properties, methods, and events. Each object
is based on a class.
• Objects equate to Nouns.
– Forms are windows.
– Controls are components contained inside a form.
• Properties equate to Adjectives.
– Color or size of a Form
• Methods are like Verbs.
– Typical methods include Close, Show and Clear
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Object Model (2 of 2)
• Events occur when the user takes action.
– User clicks a button, User moves a form
• Classes are templates used to create a new
object.
– Classes contain the definition of all available properties,
methods, and events.
– Each new object created is based on a class.
• Creating three new buttons makes each button a
instance of the Button class.
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Object Model Analogy
• Class = automobile
• Properties of automobile class= make, model,
color, engine, year
• Object = Each individual auto is an object.
– Object is also an Instance of the automobile class.
• Methods = start, stop, speedup, slowdown
• Events of automobile class = Arrive, Crash
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Visual Studio .NET
•
Included in Visual Studio .NET 2008
•
Visual Studio .NET Editions
• Visual Basic (can also be purchased separately)
• Visual C++
• C# (C sharp)
• J# (J sharp)
• F# (F sharp)
• .NET 3.5 Framework
• Express
• Standard
• Professional
• Team System
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Writing Visual Basic Projects
There is a three-step process when writing a Visual Basic
application—you set up the user interface, define the properties,
and then create the code..
•Planning
•
•
•
Design the User Interface.
Plan the Properties.
Plan the Basic Code; follow the language syntax rules; use
pseudocode then you move on to
•Programming (and use the same three-step process)
•
•
•
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Define the User Interface.
Set the properties.
Write the Basic code.
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VB Application Files
•
One Solution File—think of
one solution file equals one project
•
Solution User Options File
HelloWorld.suo
•
Form Files
HelloForm.vb
•
•
•
Resource File for the Form
HelloForm.resx
Form Designer
HelloForm.Designer.vb
Project User Options File
HelloWorld.vbproj.user
HelloWorld.sln
Once a project is run, several more files are created by the system. The
only file that is opened directly is the solution file.
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4
Visual Studio Environment
The Visual Studio environment is where you create and
test your projects. In Visual Studio, it is called an
•Integrated Development Environment (IDE) consisting of
various tools including:
•
•
•
•
•
•
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Form Designer
Editor for entering and modifying code
Compiler
Debugger
Object Browser
Help Facility
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Default Environment Settings
Visual Studio 2008
provides a new option
that allows the
programmer to select
the default profile for
the IDE.
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The IDE Initial Screen
The Visual
Studio IDE with
the Start Page
open, as it first
appears in
Windows XP,
without an open
project
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5
IDE Main Window
Toolbars
Document Window
Form Designer
Solution Explorer Window
Properties Window
Toolbox
Help
Document window
Document window
Solution Explorer
Properties window
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ToolBox
You can scroll to view more
controls.
To sort the tools in the
toolbox:
•Right-click the toolbox and
select.
•Sort Items Alphabetically from
the context menu (shortcut
menu).
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Modes
• Design Time — used when designing the
user interface and writing code
• Run Time — used when testing and running
•
a project
Break Time — if/when receiving a run-time
error or pause error
"Look at the Title Bar"
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6
Writing Your First Project
Setting Up the Project
Hello World Project
1
2
3
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Planning the Project
•
Design the user interface.
• Set up the form.
– Resize the form.
– Place a label and a
button control on the
form using the
toolbox.
– Lock the Controls in
place.
•
After the user interface is
designed, the next step is to
set the properties.
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Setting Properties
•
Label 1
Name
messageLabel
Text leave blank
•
Button 1
Name
pushButton
Text Push Me
•
Button 2
Name
Text Exit
•
exitButton
Form
Name
helloForm
Text Hello World by
your name
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Setting the Form Properties
•
•
•
The default startup
object is Form1
The name of the form
should always be
changed to adhere to
naming rules
The properties
window shows
the files properties
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Writing the Code
•
•
•
•
•
•
While the project is running, the user can perform
actions.
Each action by the user causes an event to occur.
Write code for the events you care about; the
events you want to respond to with code.
Code is written as event procedures.
VB will ignore events for which you do not write
code.
VB will automatically name event procedures as
the object name, an underscore(_) and the name of
the event.
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More on Writing the Code
• When writing the code for your first project,
you will use the following:
• Remark Statement
• Assignment Statement
• Ending a Program
• Editor Window
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Remark Statement
•
•
•
•
Also known as Comment, used for
documentation; every procedure should begin
with a remark statement providing explanation.
Non-executable
Automatically colored Green in Editor
Begins with an apostrophe ( ' )
• On a separate line from executable code
• At the right end of a line of executable code
'Display the Hello World message.
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Assignment Statement
•
•
•
Assigns a value to a property or variable
Operates from right to left — the value appearing on
the right side of the equal sign is assigned to the
property named on the left of the equal sign.
Enclose text strings in quotation marks (" ")
messageLabel.Text=" Hello World "
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Ending a Program
• Methods always have parentheses. (This will help
you distinguish them from Properties which never have
parentheses.)
• To execute a method of an object you write:
Object.Method()
• Current Form may be referenced as Me
Me.Close( )
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9
Editor Window
• Declarations
Section
• Class list
• Method list
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Run, Save, Modify, Print, Test, Debug,
and Execute
•
Run Project
•
•
•
•
•
Save Project — File Menu, Save All.
Modify Project if needed.
"Help is always available from the
Print the Code.
Help Menu or by pressing F1."
Correct any Errors and Rerun.
When you start executing your program, the first step is
called compiling, which means that the VB statements are
converted to Microsoft Intermediate Language (MSIL).
Your goal is to have no errors during the compile process:
a clean compile.
• Open Debug Menu, Start Debugging.
• Start Debugging button on the toolbar.
• Press F5, the Start Debugging command.
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Print the Code
• File Menu, Print
• Prints complete code listing
• Uses arrow symbol to denote line
continuation
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Finding and Fixing Errors
•
Syntax Errors
• Breaks VB’s rules for punctuation, format, or spelling
• Smart editor finds most syntax errors, compiler finds the rest.
• The editor identifies a syntax error with a squiggly blue line
and you can point to an error to pop up the error message.
• You can display the Error List window and line numbers in the
source code to help locate the error lines.
•
Run-Time Errors
•
Logic Errors
• Statements that fail to execute, such as impossible arithmetic
operations
• Project runs, but produces incorrect results.
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Naming Rules and Conventions
•
•
•
Have a set of standards and always follow them.
No spaces, punctuation marks, or reserved
words
Use camel casing.
• Examples
–messageLabel
–exitButton
–dataEntryForm
–paymentAmountTextBox
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Recommended Naming Conventions for VB
Objects
Object Class
Example
Form
dataEntryForm
Button
exitButton
Label
totalLabel
TextBox
paymentAmountTextbox
Radio button
boldRadiobutton
CheckBox
printSummaryCheckBox
Horizontal Scroll Bar
rateHorizontalScrollBar
Vertical Scroll Bar
temperatureVerticalScrollBar
PictureBox
landscapePictureBox
ComboBox
bookListComboBox
ListBox
ingredientsListBox
SoundPlayer
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introPageSoundPlayer
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Visual Studio Help Additional Info (1 of 2)
•
•
•
•
Visual Studio has an extensive Help facility.
Filter MSDN help to display VB topics only.
Run MSDN from hard drive, CD, or Web.
You can access MSDN on the Web at
http://msdn.microsoft.com
•
The Help system display is greatly changed and
improved in Visual Studio 2008. You view the Help
topics in a separate window from the VS IDE, so you
can have both windows opened at the same time.
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Visual Studio Help Additional Info (2 of 2)
•
When you choose How
Do I, Search, Contents,
Index, or Help
Favorites from the Help
menu, a new window
opens on top of the IDE
window. You can
switch from one
window to the other, or
resize the windows to
view both on the screen
if your screen is large
enough.
Index Results window
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Main Document window
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