Variables

Variable types

There are different variable types for different purposes. In Visual Basic 6 the following variable types are available:

• Array
• Boolean
• Byte
• Currency
• Date
• Double
• Integer
• Long
• Single
• String
• Variant

You declare a variable by using the Dim keyword:

Dim RandomNumber As Integer

If you do not specify a variable type the variable will default to Variant:

Dim Foo

is equivalent to

Dim Foo As Variant

Boolean

Boolean is the simplest variable type as it can contain only one of two values: True or False.

Foo = True
Bar = False

Booleans can be used to control the flow of code:

Dim Foo as Boolean
Foo = True

If Foo Then
  MsgBox "True"
Else
  MsgBox "False"
End If

Integer

An integer is a numeric data type and can contain a 16-bit signed value (-32768 to +32767). If you know that a variable will only contain whole numbers (such as 9) and not fractional numbers (such as 5.43), declare it as an integer (or long) datatype.

Dim RandomNumber As Integer
RandomNumber = 9

Integers are commonly used as counters in For...Next loops:

Dim Counter As Integer

For Counter = 0 to 2
  MsgBox Counter
Next Counter

Trying to assign a value less than -32768 or greater than 32767 to an integer will result in a run-time error:

Dim MyNumber As Integer
MyNumber = 40000  'Run-time error '6': Overflow

String

A string variable can contain an empty text, a character, a word or a text of variable length. The string value must be contained in quotation marks (").

Dim Fruit as String
Fruit = "Banana"

If you need quotation marks inside a string literal you use two subsequent quotation marks ("").

Dim Quote as String
Quote = "Bill says: ""Learn VB!"""