Dim Counter As Integer
	Dim NumberOfBytes As Long = 20000
	Dim InterestRate as Double = 8.125
	Dim Letter As Char = "A"
	Dim Line1 As String = "This is a string"
						

• A variable stores a value that can change as the program executes.
• You must declare a variable with the Dim statement before you can use it.
• You may initialize a variable when you declare it. If you do not Visual Basic assigns:
• A value of 0 to all numeric types.
• A value of false to Boolean types.
• An Empty String to String Values.

Figure VB-35: Visual Basic Variable Declaration Syntax and Examples

	Const DaysInOctober As Integer = 31
	Const StateSalesTax As Double = .07
						

• A constant stores a value that can't be changed.
• A literal value refers to a specific numeric value like 2.5 or 1.7

Figure VB-36: Visual Basic Constant Declaration and Syntax

• An arithmetic expression consists of one or more operands and arithmetic operators.
• The first seven operators in the table above are called binary operators
because they work on two operands.
• The last two operators are called unary operators because they work on one operand.

Figure VB-37: Visual Basic Arithmetic Operators

	Counter = 21
	NewCounter = Counter
	Total = Subtotal * DiscountAmount
	Price = Price + .57
	Price += .57
						

• Assignment Statement: Consists of a variable, an equals sign, and an expression.
• When the Assignment Statement is executed:
• The expression is evaluated.
• The result of the operation stored in the variable.
• In addition to the equals sign, Visual Basic provides 5 additional assignment operators.
• These operators provide a shortcut assignment method.

Figure VB-38: Visual Basic Arithmetic Assignment Operators

1. Exponentiation.
2. Positive and Negative.
3. Multiplication, Division, Integer Division, Modulus.
4. Addition and Subtraction.

	Dim DiscountPercent As Double = .2			' 20% Discount
	Dim Price As Double = 100				' Price of $100
	Price = Price * 1 - DiscountPercent			' Price = $99.80

	Dim DiscountPercent As Double = .2			' 20% Discount
	Dim Price As Double = 100				' Price of $100
	Price = Price * (1 - DiscountPercent)			' Price = $80.00
						

• Operations in an expression are evaluated from left to right in the order of precedence.
• When Parentheses are used:
• The operations in the innermost sets of parentheses are done first.
• Subsequent sets working towards the outermost sets of parentheses are done next.

Figure VB-39: Visual Basic Operator Order of Precedence

	Dim Grade As Double = 92			' Converts an Integer to Double
	
	Dim A As Double = 6.5
	Dim B As Integer = 6
	Dim C As Integer = 10

	Dim Ave As Double = ( A + B + C ) / 3		' B & C & 3 will be converted to Double
							' Ave = ( 22.5 / 3.0 ) = 7.5
						

	Dim Grade As Integer = 93.75					' Grade = 94 due to rounding

	Dim Subtotal As Double = txtSubtotal.Text			' May throw exception
	
	Dim Average As Integer = ( A + B + C ) / 3			' Average = 8
						

	Dim Grade As Integer = CInt( 93.75 )				' Grade = 94 due to rounding

	Dim Subtotal As Double = CDbl ( txtSubtotal.Text )		' May throw exception

	Dim Average As Integer = CInt ( CInt ( A ) + B + C ) / 3	' Average = 7
						

• The process of converting one data type to another is called Casting.
• A Widening Conversion transforms lower precision data to higher precision.
• Visual Basic does Widening Conversion automatically.
• A Narrowing Conversion transforms higher precision data to lower precision.
• In order to avoid exceptions - it is best to perform casting explicitly.

Figure VB-40: Visual Basic Type Casting Examples and Description