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IS 118 1
IS 118 Introduction to Development Tools
VB Chapter 01-02
IS 118 2
Things to Cover
What is Visual Basic – (VB) How it operates vs. Others Sound Program Criteria
Chapter 2 The IDE Forms, and Controls Events, properties and methods Coding and Naming conventions Running Executables
IS 118 3
Note
For These chapters we will follow the book and you should follow along on your computer as we do it
IS 118 4
Evolution of Visual Basic
Evolved from BASIC (Beginner’s All-Purpose Symbolic Instruction Code) Designed to provide interactive computing on
mainframe computersWidely available on early microcomputersIntroduction of personal computers (early
1980’s) Microsoft introduced GW-Basic with the DOS
operating system
IS 118 5
Language Processors
Required to process programs into a program the computer can understand
Interpreters Read, interpret, and carry out one line of code at a time
Compilers Translate a source program (i.e. one written in VB) Create an object program (one a machine can read)
Object programs also called “executables” Compiled programs run much faster
IS 118 6
Characteristics of Visual Basic Provides visual objects (controls) that can be
drawn onto a window (form) Makes building the interface much easier
Object-oriented code structure Code structured around objects
Easy to understand syntax “IntelliSense” technology helps write code
Objects can be reused and extended through inheritance
Event-driven language Things happen in response to events
Examples of events: mouse click, opening or closing a window
The user, not the program determines the sequence of operations
IS 118 7
Creating a VB Program
Takes place in the Visual Studio Integrated Development Environment (IDE) Provides an environment for creating the interfaces,
writing and testing code, and making changes Provides the .NET framework for Web services, Visual
C#.NET, Visual Basic.NET, etc.
Statement: an instruction that can stand alone Code: a group of statements
IS 118 8
Overview of VB Program DevelopmentCriteria of a sound application
Internal criteria geared to the programmer External criteria geared to the user
Program development cycle Understand distinct steps in the process of
developing an application
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External Criteria Functionality
Does the program do what it is supposed to do?
Efficiency Program should minimize the use of computer
resources Includes memory, processing time, and storage
space
User-Friendliness Make the application easy to use
Includes helpful error messages, guarding against user errors, consistent appearance and behavior of windows
IS 118 10
Internal Criteria Consistency in coding style
Following conventions most programmers follow Indenting blocks of code Naming objects with predefined prefixes
Code clarity and readability Use meaningful variable names Adding comments to code can aid understanding
Modularity in code design Each block of code is isolated from the rest of the
program Easier to debug, review, and revise
IS 118 11
Internal Criteria
Elegant algorithms Algorithm: a systematic approach to solving the
programming problem Logic easy to trace and implement Efficient in terms of speed and storage
requirementsCode maintainability
General applicability: code will not require revision even if the program requirements change
IS 118 12
Steps in Developing a Program
Developing an application requires several distinct steps
Skipping or not giving careful attention to steps can create a lot of rework, headaches, and expense Mistakes made in the earlier stages of program
development require much more time, money, and hassle to rework
IS 118 13
Steps in Program DevelopmentAnalyze and define the problem
Program must meet application needs
Design the visual interface Decide what data fields appear and the
appropriate controls
Define User-Program Interaction Define events, both user actions and system
activities
IS 118 14
Steps in Program Development
Design the code structure Structure dictated by responses program
should carry out Well-designed code enhances maintainability
Write Code Develop code based on your analysis of the
problem and design of the structure
IS 118 15
Steps in Program Development
Test and edit the program Various error types:
Syntax errors: failure to follow programming rules Semantic errors: failure to say what you mean Logic errors: difference between what programmer
thinks code will do and what it actually does
Place the program into production Production program works with live data and
produces “real” results
IS 118 16
Learning the Language
Comparing learning a spoken language and learning a programming language
Vocabulary Types of objects, methods, and events
Grammar Syntax rules
Semantics Meaning of how programming constructs fit together
Effectiveness Finding better ways to express the same idea
IS 118 17
Hands-on Practice
Programming is a skill, like playing a sport or a musical instrument
Practice enables you to gain familiarity with: The IDE The vocabulary and syntax rules of VB How different parts of the code fit together Identify opportunities for code improvement
IS 118 18
The IDE –lets do it
IS 118 19
Summary
Visual Basic evolved from BASICVisual elements allow easy changes in
user interfaceObject-oriented syntax makes it easier
to learn vocabulary and syntaxObject-oriented language enhances
code reusability Inheritance allows programmer to reuse code
IS 118 20
Summary
Sound programs must meet internal criteria and external criteria
There are distinct steps in developing code. Don’t try to shortcut the early stages
Learning a programming language is like learning a spoken language
PRACTICE, PRACTICE, PRACTICE
Copyright (c) 2003 by Prentice Hall
Chapter 2Introduction to Visual Basic
Programming
Visual Basic.NET
IS 118 22
Objectives
Navigate the IDECreate controls on a form and adjust their
sizesUnderstand the events, properties, and
methods of controlsUnderstand how the code and events work
in a VB program
IS 118 23
Objectives
Open and save a VB projectUnderstand the coding mechanics and the
naming conventionGet help from the MSDN help systemEnumerate the types of statements in a
programRun an executable without the IDE
IS 118 24
The IDE Profile
IS 118 25
Starting the IDE
The Visual Studio Start Page
IS 118 26
Starting a New ProjectDefault: Windows Application
IS 118 27
The Integrated Development Environment (IDE) Menu bar provides many menu items
Examples include File and Edit menus
Toolbar lies below menu bar Provides shortcuts to the menu bar
Toolbox Contains various icons representing VB controls
Solution Explorer Shows all forms, references, classes, and modules the
current project contains
IS 118 28
The IDEMenu bar
Toolbar
Blank form in IDE
Toolbox
IS 118 29
Solution Explorer and Properties Window
Solutions Explorer shows all the forms, references, classes, and modules in the project
Properties window shows all the properties of the selected object
IS 118 30
Your First Visual Basic Program
Form contains a label and a button
Double-click the button on the form to open the code window
IS 118 31
The Code Window
Tabs at top let you toggle between the form and the code window
Comments appear green in the IDEObject-oriented syntax: object
and property separated by dot (period)
Procedure box lists events the object in the object box recognizes
Object box lists all objects in the form
IS 118 32
When You Run the Program
Label changes when you click the Say Welcome button
IS 118 33
Understanding the IDE
Design time When you are placing controls on the form When you are writing code in the code window
Runtime When the code in your project comes to life,
responding to events Press Start on the Debug menu in the IDE Press the F5 key in the IDE Press the start button in the IDE
IS 118 34
Coding Mechanics
Comments Used to provide clues to the purpose of the code Begin with tick mark (apostrophe) or Rem Appear green in the IDE
Showing Blocks of Code The IDE will help indent the code lines
Line Continuation If you have to write a long statement, break into lines by
using the underscore (_) character
IS 118 35
Interfaces of VB Objects
Forms and controls are objectsObjects have interfaces:
Properties: typically relate to appearance of objects
Events: user or system actions recognized by the object
Procedures written to handle events Methods: actions that objects are capable of
performing
IS 118 36
PropertiesSpecial types of data associated with
objectMost relate to appearance of objects
i.e. Label1.BackColor = Color.Red
Some relate to behavior of objects i.e. btnNext.Enabled – True
Object and property separated by dot (period)
Property must be given a value
IS 118 37
EventsUser or system actions the object
recognizes i.e. a button has a Click event
Event procedure Procedure written to handle a specific event Also called event handler
Syntax: Private Sub ObjectName_Event Code surrounded by Sub … End Sub Private refers to the scope of the procedure Object and event separated by underscore
IS 118 38
Methods
Actions objects are capable of performing i.e. Me.Close()
Syntax: Object.Method(Parameter List) Parameter list: arguments passed in to the
method Parameter list must be enclosed in
parentheses, even if no parameters are required
IS 118 39
Getting Help from the Help Menu
Enter search term in the Look for box
Double-click an item in the list box
Double-click an item in the lower center pane; upper center pane shows results
IS 118 40
Naming objects
When naming objects, be descriptive Use standard prefixes, i.e. lbl for label Give the object a meaningful name
i.e. a label with text “Name” could be lblName
Change the object name in the Properties window
Name objects before placing code in the code window
IS 118 41
Assignment Statements
Generate some sort of result i.e. moving data from one location in memory to
another
Syntax: lblWelcome.Text = “Welcome” Expression on right hand side of equation
moved to memory location on left hand side
Most common statements in VB programs
IS 118 42
Statements That Direct Execution Flow Conditional Execution
One block of code executed if a statement is true; a different block executed if false
If block is most common example
Repetition When you need to execute a block of code repetitively For…Next loop is most common
Code that “Jumps” Exit Sub exits a procedure
IS 118 43
Completing the Development CycleProgram must be compiled into executable
When you test run your program, the IDE compiles and saves the executable
To run the program: Double-click the executable Use the Run option off the Start menu Add the executable to your Start menu
IS 118 44
Finding the Executable
Executable is found in the /bin folder underneath the folder containing your project.
In this case: C:\My Documents\ Visual Studio Projects\Welcome
IS 118 45
Summary Start the IDE from the Start Menu
Choose Visual Studio.NET from Programs menu
Edit your profile to customize environment Menu bar gives you all menu items. Toolbar
offers shortcuts to menu items Toolbox contains controls and components The form allows you to design visual elements
Code window behind form is where you place code
Solution Explorer shows all files in your solution
IS 118 46
Summary Properties window shows properties of selected
object To develop a program
Draw and adjust the controls on the form Set properties of the objects Place code in events, then test and revise
The IDE allows you to write and compile the program
Use comments in your code to show the purpose of the code
Break long code lines with an underscore character
IS 118 47
Summary
Objects have three types of interfaces: properties, methods, and events
VS.Net help file provides a wealth of information Follow object naming conventions
Use predefined prefixes for objects Give objects meaningful names
Two types of programming statements: Those that produce results Those that control program flow
IS 118 48
Summary
Four types of objects introduced: Form used for visual interface Label used to display text to give clues Button used to trigger actions Timer used to keep track of time
IDE automatically produces the executable when you develop the program
Run the executable like other Windows programs
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