CBVP2103

Evolved from BASIC

Beginner‟s All-Purpose Symbolic Instruction Code

Introduction to programming for novices

Introduced by Microsoft (1991)

Made programming for Windows much easier

• IDE facilitates quicker programming

Rapid Application Development

• Provided many extra features

Event handling

Graphical user interfaces

Object-oriented programming

Motivated by popularity of electronic devices

Provide interaction between wide variety of devices◦ Web-based applications distributed to different

devices

Cell phones

Personal Digital Assistants

Personal computers

◦ Allow communication between programs of disparate languages

Enhanced object orientation◦ Powerful library of components

Application development made even quicker

Enhanced language interoperability◦ Interaction between different languages

Old software compatible with Visual Basic .NET programs

Interaction over the Internet

Simple Object Access Protocol (SOAP)

Extensible Markup Language (XML)

Promotes use of Web services

Introduced by Microsoft (June 2000)◦ Vision for embracing the Internet in software

development

Independence from specific language or platform◦ Applications developed in any .NET compatible language Visual Basic .NET, Visual C++ .NET, C# and more

◦ Programmers can contribute to applications using the language in which they are most competent

Architecture capable of existing on multiple platforms

New program development process◦ Provides increased productivity

Additional information available at Microsoft Web site www.microsoft.com/net

Heart of .NET strategy◦ Manages and executes applications and Web services◦ Provides security, memory management and other

programming capabilities

Includes Framework class library (FCL)◦ Pre-packaged classes ready for reuse◦ Used by any .NET language

Details contained in Common Language Specification (CLS)◦ Submitted to European Computer Manufacturers

Association to make the framework easily converted to other platforms

Executes programs by Common Language Runtime (CLR)

Base Class LibraryBase Class Library

Common Language SpecificationCommon Language Specification

Common Language RuntimeCommon Language Runtime

ADO.NET: Data and XMLADO.NET: Data and XML

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Visual Studio .NET◦ Microsoft‟s Integrated Development Environment

(IDE)

◦ Used to create, run and debug programs (applications)

Visual programming◦ Dragging and dropping predefined building blocks

into place to create a simple Visual Basic program

Start Page in Visual Studio .NET.

Location bar

New Project dialog.

Design WindowT

oolbox

SolutionExplorer

PropertiesWindow

Menu Desc rip tion

File Contains commands for opening projects, closing projects, printing project data,

etc.

Edit Contains commands such as cut, paste, find, undo, etc.

View Contains commands for displaying IDE windows and toolbars.

Project Contains commands for managing a project and its files.

Build Contains commands for compiling a program.

Debug Contains commands for debugging (i.e., identifying and correcting problems in a

program) and running a program.

Data Contains commands for interacting with databases (i.e., files that store data,

which we discuss in Chapter 19, Databases, SQL and ADO .NET).

Format Contains commands for arranging a form’s controls.

Tools Contains commands for accessing additional IDE tools and options that enable

customization of the IDE.

Windows Contains commands for arranging and displaying windows.

Help Contains commands for accessing the IDE’s help features.

Fig. 2.5 Summary of Visua l Stud io .NET IDE menus.

Comma nd Desc rip tion

Contents Displays a categorized table of contents in which help articles are

organized by topic.

Index Displays an alphabetized list of topics through which the programmer

can browse.

Search Allows programmers to find help articles based on search keywords.

Fig. 2.13 Help menu c ommands.

Simple program executing.

Creating a new Windows Application.

Setting the project location in the Project Location dialog.

Fig. 2.18 Setting the form‟s Text property.

Form with sizing handles.

Changing the form‟s BackColor property.

Adding a label to the form.

Form elements are objects called controls

This form has:

◦ Two TextBox controls

◦ Four Label controls

◦ Two Button controls

The value displayed by a control is held in the text property of the control

Left button text property is Calculate Gross Pay

Buttons have methods attached to events

Should be meaningful 1st 3 lowercase letters indicate the type of

control◦ txt… for Text Boxes◦ lbl… for Labels◦ btn… for Buttons

After that, capitalize the first letter of each word

txtHoursWorked is clearer than txthoursworked Change the name property

◦ Set the name of button1 to btnWelcome◦ Set the name of button2 to btnExit

The GUI environment is event-driven

An event is an action that takes place within a program◦ Clicking a button (a Click event)

◦ Keying in a TextBox (a TextChanged event)

Visual Basic controls are capable of detecting many, many events

A program can respond to an event if the programmer writes an event procedure

An Event Procedure is a block of code that executes only when particular event occurs

Writing an Event Procedure◦ Create the event procedure stub

Double click on control from Design Window – for default event for that control

OR

Open the Code Editor (F7 or View Menu/Code option)

Select Control & Select Event from drop down windows in Code Editor

◦ Add the event code to the event procedure stub

Select the btnWelcome control from the Form Controls List Box

Select the Click event from the list of many available events

Buttons have 57 possible events they can respond to

Beginning of Procedure is created for you◦ If you create stub by double clicking on control it

will create a stub for the most commonly used event for that control

Write the code that you want executed when the user clicks on the btnWelcome button◦ Type: MsgBox (“Welcome to Visual Basic”)

◦ Must be contained within the Event Procedure Stub

Not Case Sensitive◦ Visual Basic will “correct” case issues for you

Keywords are in Blue◦ Special reserved words

Comments in Green

Problems with Syntax (Language) will be underlined in blue

Rules◦ Use spaces to separate the words and operators

◦ Indentation and capitalization have no effect

Recommendations◦ Use indentation and extra spaces for alignment

◦ Use blank lines before and after groups of related statements

◦ Code all variable declarations at the start of the procedure

◦ Group related declarations

Usage◦ Type an apostrophe ( ' ) followed by the comment

◦ The compiler ignores everything on the line after „

◦ Used for documentation/readability and to disable chosen statements during testing

Recommendations◦ Follow apostrophe with a star for readability ( „* )

◦ Use at beginning of program to indicate author, purpose, date, etc.

◦ Use for groups of related statements and portions of code that are difficult to understand

Public Class Form1

Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventAr…

'*Variable declarationsDim dOrderTotal As DecimalDim dDiscountAmount As Decimal

'*Get total from textbox dOrderTotal = txtOrderTotal.Text

'*Calculate the proper discountdDiscountAmount = dOrderTotal * 0.25'dDiscountAmount = dOrderTotal * 0.25

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)…

'*Code goes here

End Sub

End Class

Create an Event Procedure for when the btnExit button is clicked

Have it display “Goodbye” in a MsgBox

Then “End” – this will terminate the program

Make sure to save your work◦ SAVE ALL (not Save Form)

◦ Visual Basic applications are

◦ made of several files -

◦ Often even several forms