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Variable Arrays

• A list of variables, all of the same type, with similar meaning but different values each one having an index number
• Can be any valid variable
• Example: Putt-Putt scores

Syntax

• Dim hole(18) As Integer
      hole (0) = 1
      hole (1) = 2
      hole (2) = 3

Initialization

• Individual numeric array elements are initialized to zero by default
• You, the programmer can explicitly initialize the array with assignment statements as in the previous slide

Bounds versus Index

• The position number contained within parentheses is called an index
• Declaring the variable - Dim numbers (5) As Integer - would tell the computer to reserve 6 elements for an Integer array of numbers
     - the value 5 defines the upper bound (highest value) of numbers
     - the lower bound of numbers defaults to 0
• When an upper bound is specified in the declaration, a fixed-size array is created

Uses

• A variable array frequently used in a for-next loop
• The upper bound is frequently a constant
• Used when you want to be able to have multiple values for properties (e.g., the same label used to display three different captions at different times)
• Used when you are keeping track of a list or table of data (e.g., your grades)

Control Arrays

• Conceptually similar to variable arrays
• Are an array of controls of the same type and all controls in an array share the same properties as a default (properties can be changed through code individually)
• All controls in an array share the same code box
• All events related to a code array automatically pass an Index parameter

Using a Control Array

• Used when several controls need to do the same thing (e.g., color box)
• Example: you want to store images off-screen for quick access

Creating a Control Array

• Create the first object in the regular way
• Set the properties of this object ESPECIALLY the name
• Copy the object, paste it - a dialog box will ask you if you want to create an array
• Click "YES" and move the new object wherever you want it. Continue this process until you have all you need.

Constants

• Treated much like variables in code except:
  - the value of a constant cannot change during the execution of the program
  - a constant cannot be given a new value during the run of the program

Uses of a constant

• A constant would be used to name a number so it is easier to use in code
• Example: PI = 3.1415927
• A constant would be used to refer to a commonly occurring value in a program
• Example: NumPics = 3

Additional uses

• If the programmer updates the program to handle more frames, he only has to change the constant definition - this saves time and makes the program easier to read

Syntax

• CONST Identifier = Value

Image boxes

• Are a control to handle pictures and the property of the picture determines what image is shown
• The picture can be copied to the clipboard, loaded from a disk file or copied from another object
• The image box automatically resizes itself to the picture size and can be used to scale pictures

Special property

• The image box has a special property - visible that is used to hide pictures "off stage"
• Syntax: ControlName.visible = True or False
• True means the control is visible and is the default
• False means the control is invisible

Multitasking as a programming tool

• Multitasking is the ability to run multiple program simultaneously on the same processor
• Multitasking is commonly used when defining graphic elements of a visual basic program
• Visual Basic has limited drawing features of its own but allows use of Windows Opaint or other specialized drawing programs
• It also allows the programmer to define icons, sound effects, and other elements using specialized tools