VBA Declaring Variables
Type Hints
Type Hints are heavily discouraged. They exist and are documented here for historical and backward-compatibility reasons. You should use the As [DataType] syntax instead.
Public Sub ExampleDeclaration()
Dim someInteger% '% Equivalent to "As Integer"
Dim someLong& '& Equivalent to "As Long"
Dim someDecimal@ '@ Equivalent to "As Currency"
Dim someSingle! '! Equivalent to "As Single"
Dim someDouble# '# Equivalent to "As Double"
Dim someString$ '$ Equivalent to "As String"
Dim someLongLong^ '^ Equivalent to "As LongLong" in 64-bit VBA hosts
End SubType hints significantly decrease code readability and encourage a legacy Hungarian Notation which also hinders readability:
Dim strFile$
Dim iFile%Instead, declare variables closer to their usage and name things for what they're used, not after their type:
Dim path As String
Dim handle As IntegerType hints can also be used on literals, to enforce a specific type. By default, a numeric literal smaller than 32,768 will be interpreted as an Integer literal, but with a type hint you can control that:
Dim foo 'implicit Variant
foo = 42& ' foo is now a Long
foo = 42# ' foo is now a Double
Debug.Print TypeName(42!) ' prints "Single"Type hints are usually not needed on literals, because they would be assigned to a variable declared with an explicit type, or implicitly converted to the appropriate type when passed as parameters. Implicit conversions can be avoided using one of the explicit type conversion functions:
'Calls procedure DoSomething and passes a literal 42 as a Long using a type hint
DoSomething 42&
'Calls procedure DoSomething and passes a literal 42 explicitly converted to a Long
DoSomething CLng(42)String-returning built-in functions
The majority of the built-in functions that handle strings come in two versions: A loosely typed version that returns a Variant, and a strongly typed version (ending with $) that returns a String. Unless you are assigning the return value to a Variant, you should prefer the version that returns a String - otherwise there is an implicit conversion of the return value.
Debug.Print Left(foo, 2) 'Left returns a Variant
Debug.Print Left$(foo, 2) 'Left$ returns a String