Lecture 2
Introduction to
Visual Basic.NET
Programming Appreciation
About Your Lecturer
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Richard C.Y. Pang
Computer & Information
Management
Room 436
Consultation Hours
Telephone - 2595 8168
Email: richardp@vtc.edu.hk
Consultation Hours
Wed 11am - 5pm
Thu 2pm - 4pm
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Textbook
• Programming in Visual Basic .NET
[4th ed.]
– by Bradley, Julia Case
– New York, N.Y. : McGrawHill/Irwin, c2003.
– IVE Library: QA 76.73 .B3 B697
2003
Reference Book
• Visual Basic .NET Introductory Concepts
and Techniques
– Gary B. Shelly, Thomas J. Cashman, Jeffrey J.
Quasney
– Thomson Course Technology
– ISBN 0-7895-6547-1
• Any book on Visual Basic .NET
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Writing Windows
Applications with VB
• Windows Graphical User Interface
• Window = Form
• Toolbox of elements called Controls
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Text Box
Label
Check Box
Button
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Programming Languages
• Procedural
– Program specifies exact sequence
• Event Driven (VB 6.0 and previous)
• Object Oriented Programming (VB.NET)
– User controls sequence
• Click event
• Double Click event
• Change event
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Object Model
• Object ==> Noun
– Form and Controls
• Property ==> Adjective
– Color of a Form
• Method ==> Verb
– Move a Form
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Object Model (cont.)
• Event ==> Occur when the user takes action
– User clicks a button, User moves a form
• Class ==> Template to create new object
– Each control added is an Instance of a Class
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Dot Notation
• Used to reference object's properties and
methods in code
– Object dot Property
• Form.Text, TextBox.Text
– Object dot Method
• Form.Hide( ), TextBox.Focus( )
• To reference an object's events use an
underscore instead of a dot
• Button_Click, ListBox_TextChanged
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Object Model Analogy
• Class = automobile
• Properties = make, model, color, year
• Object = each individual car
– Object is also an Instance of the automobile
class
• Methods = start, stop, speedup, slowdown
• Events = car arrives, car crashes
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Visual Basic.NET
• Included in Visual Studio.NET
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Visual Basic (can also be purchased separately)
C++
C#
.NET Framework
• Complete rewrite from VB Version 6
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Visual Studio.NET Editions
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Academic
Professional
Enterprise Developer
Enterprise Architect
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Steps for Writing VB Projects
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Design/Define the User Interface
Plan/Set the Properties
Plan/Write the Code
Test and Debug
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
VB Application Files
Open this file directly to work on a Project
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One Solution File
Solution User Options File
Project Files
Project User Options File
Form Files
Resource File for the Form
.sln
.suo
.vbproj
.vbproj.user
.vb
.resx
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Visual Studio Environment
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Integrated Development Environment (IDE)
Form Designer
Editor for entering code
Compiler
Debugger
Object Browser
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Visual Studio IDE Start Page
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
IDE New Project Dialog
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
IDE Main Window
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Toolbars
Document Window
Form Designer
Solution Explorer
Properties Window
Toolbox
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
IDE Main Window
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
VB Toolbox
• Holds the tools
you place on a
form
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Visual Studio Help
• Extensive Help feature
• Includes Microsoft Developer Network
library (MSDN)
• Entire reference manual
• Coding examples
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Modes
• Design Time
• Run Time
• Break Time
“Look at the Title Bar”
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Naming Rules (p 43-44)
• Always use standard names for objects
• No spaces or punctuation marks
• 3 letter lowercase prefix identifies control
type
• Button-btn
• Label-lbl
• Form-frm
• If multiple words capitalize 1st letter of
each word
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Recommended Naming
Conventions for VB Objects
Object Class
Form
Button
TextBox
Label
Radio Button
CheckBox
Horizontal ScrollBar
Vertical ScrollBar
PictureBox
ComboBox
ListBox
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Prefix
frm
btn
txt
lbl
rad
chk
hsb
vsb
pic
cbo
lst
Example
frmDataEntry
btnExit
txtPaymentAmount
lblTotal
radBold
chkPrintSummary
hsbRate
vsbTemperature
picLandscape
cboBookList
lstIndegredients
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Hello World Project (p 15)
Design the User Interface
lblMessage
btnPush
btnExit
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Properties Window-Label1
Rename Label1
to lblMessage
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Set the Properties
• Label
– Name
– Text
lblMessage
leave blank
• Button 1
– Name
– Text
btnPush
Push Me
• Button 2
– Name
– Text
btnExit
Exit
• Form
– Name
– Text
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frmHello
Hello World by your name
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Set the Project's Startup
Object
• The default startup object if Form1
• The name of the form should always be
changed to adhere to naming rules
• Using Project menu, Properties change the
startup object to match the new name
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Project Property Page Dialog
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Write 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 with code
• Code is written as event procedures
• VB will ignore events for which you do not
write code
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Editor Window
• Declarations Section
• Class list
• Method list
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Remark Statement
• Also known as Comment, used for
documentation
• 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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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Assignment Statement
• Assigns a value to a property or variable
• Operates from right to left
• Enclose text strings in quotation marks (" ")
lblMessage.Text=" Hello World "
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Ending a Program
• Execute the Close Method of the Form
• Methods always have parentheses (this will
help you distinguish them from Properties which
never have parentheses)
• Current Form may be referenced as Me
Me.Close( )
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Test and Debug
• Save Project - File Menu, Save All
• Run Project
– Debug Menu, Start
– Start Without Full Compile
– Start With Full Compile
(F5)
(CTRL F5)
• Correct any Errors and Rerun
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Compile errors
Run-Time Errors
Logic errors
Syntax errors
"Help is always available from the
Help Menu or by pressing F1."
© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Print the Code
• File Menu, Print
• Prints complete code listing
• Uses arrow symbol
to denote line
continuation
• Examine sample output on page 39
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.
Finding and Fixing Errors
• Syntax Errors
• Run-Time Errors
• Logic Errors
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© 2001 by The McGraw-Hill Companies, Inc. All rights reserved.