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Introduction to Visual Basic.NET 2005
Chapter11
McGraw-Hill © 2006 The McGraw-Hill Companies, Inc. All rights reserved.
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Chapter Objectives (1 of 2)
Describe the process of visual program design and development
Explain the term object-oriented programmingExplain the concepts of classes, objects, properties,
methods, and eventsList and describe the three steps for writing a Visual
Basic projectDescribe 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 timeWrite, run, save, print, and modify your first Visual
Basic projectIdentify syntax errors, run-time errors, and logic
errorsUse Auto Correct to correct syntax errorsLook up Visual Basic topic in Help
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Writing Windows Applications with VB(1 of 2)
Windows Graphical User (GUI) InterfaceDefines how elements look and function
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Writing Windows Applications with VB(2 of 2)
Elements are called controls and are added using a toolbox
Windows are called forms
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Programming Languages-Procedural, Event Driven and Object Oriented
Procedural—Cobol, Fortran, BasicProgram specifies exact sequence of all operations
Event Driven (VB 6.0 and previous)Contain some elements of Object oriented programming but
not all
Object Oriented Programming (OOP) (VB .NET)User controls sequence
Click eventDouble Click eventChange event
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The Object Model (1 of 2)
In VB you will work with objects, which have properties, methods, and events. Each object is based on a class.
Objects equate to NounsForms are windowsControls are components contained inside a form
Properties equate to AdjectivesColor or size of a Form
Methods are like VerbsTypical methods include Close, Show and Clear
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Object Model (2 of 2)
Events occur when the user takes actionUser clicks a button, User moves a form
Classes are templates used to create a new objectClasses contain the definition of all available properties,
methods, and eventsEach 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 = automobileProperties = make, model, color, yearObject = each individual car
Object is also an Instance of the automobile class
Methods = start, stop, speedup, slowdownEvents = car arrives, car crashes
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Visual Studio .NET
Included in Visual Studio .NET 2005Visual Basic (can also be purchased separately)Visual C++C# (C sharp)J# (J sharp).NET 2.0 Framework
Visual Studio .NET EditionsStandardProfessionalEnterprise DeveloperEnterprise Architect
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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
1. Design the User Interface
2. Plan the Properties
3. Plan the Basic Code; follow the language syntax rules; use pseudocode (English expression or comment describing action) then you move on to
Programming (and use the same three step process)1. Define the User Interface 2. Set the properties3. Write the Basic code
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VB Application Files
One Solution File—think ofone solution file equals one project .sln
Solution User Options File .suo
Form Files .vb
Resource File for the Form .resx
Project Files .vbproj
Project User Options File .vbproj.user
Application configuration File .app.config
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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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) consists of various tools including:
Form DesignerEditor for entering codeCompilerDebuggerObject BrowserHelp facility
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Default Environment Settings
Visual Studio 2005 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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IDE Main Window
ToolbarsDocument WindowForm DesignerSolution Explorer Window Properties WindowToolbox Help
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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 projectBreak Time--if/when receiving a run-time error or
pause error
“Look at the Title Bar”
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Writing Your First Visual Basic ProjectSetting Up the Project
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2
3
Hello World Project
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Planning the Project
Design the user interfaceSet up the form
Resize the formPlace a label and a button
control on the form using the
toolboxLock 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 1Name messageLabelText leave blank
Button 1Name pushButtonText Push Me
Button 2Name exitButtonText Exit
FormName helloFormText 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 occurWrite code for the events you care about; the
events you want to respond to with codeCode is written as event proceduresVB will ignore events for which you do not write
codeVB 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 StatementAssignment StatementEnding a ProgramEditor Window
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'Display the Hello World message.
Remark Statement
Also known as Comment, used for documentation; every procedure should begin with a remark statement providing explanation
Non-executableAutomatically colored Green in EditorBegins with an apostrophe ( ' )
On a separate line from executable codeAt the right end of a line of executable code
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messageLabel.Text=" Hello World "
Assignment Statement
Assigns a value to a property or variableOperates 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 (" ")
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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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Editor Window
Declarations SectionClass listMethod list
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Run, Save, Modify, Print, Test, Debug and Execute
Run ProjectDebug Menu, StartStart (F5)
Start Without Debugging (CTRL+F5)
Save Project - File Menu, Save AllModify Project if neededPrint the CodeCorrect 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.
"Help is always available from the Help Menu or by pressing F1."
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Print the Code
File Menu, PrintPrints complete code listingUses arrow symbol to denote line continuation
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Finding and Fixing Errors
Syntax ErrorsBreaks VB’s rules for punctuation, format or spellingSmart editor finds most syntax errors, compiler finds the restThe 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
Statements that fail to execute such as impossible arithmetic operations
Logic ErrorsProject runs but produces incorrect results
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Naming Rules and Conventions
Have a set of standards and always follow themNo spaces, punctuation marks or reserved wordsUse camel casing
ExamplesmessageLabelexitButtondataEntryFormpaymentAmountTextBox
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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 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 onlyRun MSDN from hard drive, CD or WebYou can access MSDN on the Web at
http://msdn.microsoft.com
The Help system display is greatly changed and improved in Visual Studio 2005. You view the Help topics in a separate window from the VS IDE, so you can have both windows open 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.