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Project 1
Building an Application

What is Visual Basic?

• Visual Basic is itself a Windows Application
• Function: builds special- purpose Windows Applications
• Uses Graphical User Interface (GUI) of Windows in the development process
• Stand-alone application - an EXE, one that runs independently of Visual Basic

 Active Window
3 Windows in Visual Basic

1. Form Window - user interface
2. Project Window - codes for forms and modules
3. Properties Window - properties of objects on the form (defaults)

 Setting Development Environment Options

• With VB6 can build desktop applications, application components, and Internet applications
• When VB6 started, choose to open a recent, existing, or new project (must specify type of new project) (usually Standard EXE project type)

Types of Interfaces

• Multiple Document Interface (MDI) - presents windows within windows
  • MDI better suited to larger monitors with better resolutions
• Single Document Interface (SDI) - presents independent windows on the desktop

Note: Interface chosen is a personal preference

Types of Interfaces

• VB6 records the size and location of these windows when project is closed so that its integrated development environment (IDE) display the same each time you start Visual Basic

Problem in Lab : IDE may look completely different every time student comes to lab and starts Visual Basic

Arranging Toolbars and Windows

• Integrated Development Environment (IDE) contains nine different windows, all of which can be docked, or anchored, to other windows that are dockable and four toolbars that that can be docked or float in their own windows
  • All windows can be resized and located anywhere on the desktop

Design and Run Time

• Design time - when application is built
• Run time - when application is used
• Projects - applications (programs, forms, and modules)
• Form - projects always start with a form

Note: form becomes the window the application occupies on desktop

• A project can have more than one form and forms created in one project can be used in other projects (for these reasons, it is advisable to give each form a unique name)

Form Properties

• Twips - measurement of form
• Width - determines form’s width
• Height - determines form’s height
  • height and width properties of form set at design-time by changing them in properties window (used to size the form)
• Left - distance in twips between left side of desktop and left border of form
• Top - distance in twips between top of desktop and top border of form
  • top and left properties are changed by using code in the form load procedure to center the form on desktop (used to position the form)
  • StartUpPosition property can be changed at Design-Time to center the form on the Desktop

Adding and Removing Controls

• Controls - graphical images or objects
• Toolbox - group of tools in Visual Basic Window

Note: 20 intrinsic controls are in the Toolbox of Visual Basic’s standard edition.

• 2000 Additional controls available from Microsoft and from third-party vendors
• 255 controls max allowed on each form

 3 Types of Controls
(Project One)

• Label - used to display text on form (cannot be changed by user at run-time)
• Text box - used to display or enter text on form (can be changed by user at run-time)
• Command button - used during run-time to initiate actions called events

Removing Controls

1. Point to Control
2. Click left mouse button
3. Press DELETE key

Setting Properties

• Properties - characteristics or attributes of a control

  Note: set at design-time by using the properties window

• Default Values - initial values set by Visual Basic

  Note: only change values that differ from the default values

2 Sections of Properties Window

• Object box - displays name of control whose properties being set
• Properties list - displays set of properties belonging to the control 
  (Two Tab sheets)
  • Alphabetic tab sheet - lists the properties in alphabetic order
  • Categorized tab sheet - groups the properties by category

Property Examples

• Caption property - contains text that you want to appear on the control
• Text property (Text box) - value given to this property appears in text box at beginning of run-time

Note: can be changed during run-time

Property Examples

• Locked property - setting this property to true prevents the user from editing the contents of a text box (used to hold answer)
• TabIndex property - determines the order in which a control gets focus by tabbing
• TabStop property - setting this property to false causes the focus to skip this control
  • Label controls never have the capability of receiving focus, so they have no TabStop property. They do have a TabIndex property used internally by Visual Basic for other purposes.

Naming Controls

• Default names - Visual Basic assigns unique names to each control 
  (Form1, Label1, Text1, Command1)

  Note: Name and Caption of control are two different properties.

• Name - used to refer to control in program code
• Caption - title of control on user interface (form)

Event Procedures

• Events - are messages sent to an object when an application runs (clicking or dragging control)

Note: events can be the execution of code statements at run-time

• Code - actions that will occur within the application in response to specific events
• language - Visual Basic words and symbols used for computer instructions

Event Procedures

• Procedures - are groups of code statements sometimes simply called code
• Code statements are instructions to the computer written at design time for the computer to execute at run-time
• Internal documentation (comments) - text added within a procedure that explains how the code in the procedure works (begin comment line with an apostrophe (‘) or the letters Rem)

 Functions and Methods

• Function - code that transforms one or more values into a new value

  example: Val function takes whatever value given and converts it to a number, or zero if not possible

• Methods - code statements that can be applied to an object to change its attributes or behavior

  example: Setfocus method causes focus to be changed to a specific control on form (Text1.SetFocus)

Note: Visual Basic has many predefined functions and methods that you can use in your code

Writing Code

• Subroutines - event procedures in Visual Basic written in blocks of code

Note: Each block has a header and terminal statement to show where subroutine begins and ends

Note: These first and last statements are supplied by Visual Basic when you begin a new event subroutine.

Subroutine Format

Sub Command1_Click ( )

‘Display Commission Amount as val of UserInput * Rate

Text2.text = Val(Text1.text) * 0.15

Text1.SetFocus

End Sub

Note: Text in Blue supplied by Visual Basic

Coding Environment

• Text Editor - code window functions as a text editor for writing code statements (add and change options of Notepad)
• Interpreter - Visual Basic converts your statements to binary as soon as ENTER key pressed.

Note: If statement can’t be converted error message displayed

Saving a Project

• Visual Basic projects are saved as a set of files
  • Forms saved with extension .frm
    • contains graphics, additional .frx file created
  • Project saved with extension .vbp
• user specifies path and filename using Save File As dialog box and the Save Project As dialog box

Documenting an Application

• Documenting an application - refers to producing a printed record of the application

3 Parts of Print Dialog Box

1. Form Image - prints blank form at design-time
2. Code - prints code for module or entire project
3. Form As Text - prints a list of all controls and property settings that are different from their default settings

Note: must first select current module (form) or the entire project before selecting parts to print

Project 1
Building an Application
END

Program Maturity Calculator Requirements

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