Chapter 2 Introduction to Visual Basic Programming. Visual Basic.NET

Chapter 2 Introduction to Visual Basic Programming Visual Basic.NET Objectives      Navigate the IDE Appreciate the use of a form Create con...
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Chapter 2 Introduction to Visual Basic Programming

Visual Basic.NET

Objectives   

 

Navigate the IDE Appreciate the use of a form Create controls on a form and adjust their sizes Understand the events, properties, and methods of controls Understand how the code and events work in a VB program

Objectives   

 

Open and save a VB project Understand the coding mechanics and the naming convention Get help from the MSDN help system Enumerate(Number) the types of statements in a program Run an executable without the IDE

The IDE Profile

Starting the IDE

The Visual Studio Start Page

Starting a New Project

Default: Windows Application

The Integrated Development Environment (IDE) 

Menu bar provides many menu items –



Toolbar lies below menu bar –



Provides shortcuts to the menu bar

Toolbox –



Examples include File and Edit menus

Contains various icons representing VB controls

Solution Explorer –

Shows all forms, references, classes, and modules the current project contains

The IDE

Menu bar

Toolbar

Toolbox

Blank form in IDE

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

Your First Visual Basic Program

Form contains a label and a button

Double-click the button on the form to open the code window

The Code Window Tabs at top let you toggle between the form and the code window Procedure box lists events the object in the object box recognizes

Object box lists all objects in the form

Object-oriented syntax: object and property separated by dot (period)

Comments appear green in the IDE

When You Run the Program

Label changes when you click the Say Welcome button

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

Coding Mechanics 

Comments – – –



Showing Blocks of Code (Lists) –



Used to provide clues to the purpose of the code Begin with tick mark (apostrophe) or Rem Appear green in the IDE

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

Interfaces of VB Objects  

Forms and controls are objects Objects 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

Properties  

Special types of data associated with object Most relate to appearance of objects –



Some relate to behavior of objects –

 

i.e. Label1.BackColor = Color.Red (Try)

i.e. Try the Properties Tab

Object and property separated by dot (period) Property must be given a value

Events 

User or system actions the object recognizes –



Event procedure – –



i.e. a button has a Click event

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

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

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

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

Assignment Statements 

Generate some sort of result –



Syntax: lblWelcome.Text = “Welcome” –



i.e. moving data from one location in memory to another

Expression on right hand side of equation moved to memory location on left hand side

Most common statements in VB programs

Statements That Direct Execution Flow 

Conditional Execution – –



Repetition – –



One block of code executed if a statement is true; a different block executed if false If block is most common example

When you need to execute a block of code repetitively For…Next loop is most common

Code that “Jumps” –

Exit Sub exits a procedure

Completing the Development Cycle 

Program 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

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

Summary 

Start the IDE from the Start 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 –



Choose Visual Studio.NET from Programs menu

Code window behind form is where you place code

Solution Explorer shows all files in your solution

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

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

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