outline

Objects

• Characteristics
     -building blocks of Visual Basic
     - Object types already created - we make new instances
     - Object types ' borrowed' from Windows environment
     - Individual entities that are somewhat self-contained
     - Can interact with other objects
     - Some behavior 'built-in'

An object has:

• Properties - individual characteristics of the object
• Events - stimuli from the user, environment, or other objects that the object can respond to
• Methods - specialized commands that the object can do - allows you to manipulate

Selected Controls

• Form - abbreviation: frm
     - main property: varies
     - main event: load (activated whenever the form shows up on screen)
     - main uses; serves as a container for all other controls
     - background for the program
     - load event used to contain code for early in the program run

Sample Code:

• Private Sub Form_Click()
  'when clicked show in the label that this
  'is a form
  lblLabel.Caption = "This is the Form"
  End Sub

Picture box

• Main property: Picture
• Main event: click
• Abbreviation: pic
• Main uses: display graphic image on screen

Sample Code:

• Private Sub picIUPUI_Click()
  'when clicked show in the label this is a
  'picture box
  lblLabel.Caption = "This is a Picture Box"
  End Sub

Label

• Main property: caption
• Main event: click
• Abbreviation: lbl
• Main uses: primary form of text OUTPUT in VB, display text on screen show text that the user cannot directly change, works like print command in other languages

Text box

• Main property: text
• Main event: change
• Abbreviation: txt
• Main uses: primary form of text INPUT in VB, displays CHANGEABLE text on screen, often works like INPUT command in other languages

Command Button

• Main property: caption
• Main event: click
• Abbreviation: cmd
• Main uses: indicated user's desire to do something, frequently houses significant amount of program code, graphically shows being depressed, easily recognized as something to click

Sample Code:

• Private Sub cmdQuit_Click()
  'when the user clicks here end the program
  End
  End Sub

Scroll bar

• Main property: value
• Main event: change
• Abbreviation: hsc (horizontal), vsc (vertical)
• Main uses: primary form of INTEGER input in VB, allows user to input numeric value graphically, range can be determined at design time, allows little opportunity for error

Sample Code:

• Private Sub hscHorizontal_Change()
  'when the user moves the scrollbar indicate in the
  'label that this is a horizontal scroll bar
  lblLabel.Caption = "This is a horizontal scroll bar " & hscHorizontal.Value
  End Sub

Option button

• Main property: value (true or false)
• Main event: click
• Abbreviation: opt
• Main uses: allows user to check ONLY ONE of a series of options, grouped in a form or frame, when one is true all others are false, like a car radio

Check box

• Main property: value (checked, unchecked or grayed)
• Main event: click
• Abbreviation: chk
• Main uses: allows user to check one OR MORE of a series of options, can also be grouped, more than one can be checked at a time