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!"""