Visual Basic for Applications Reference
Declares variables and allocates storage space.
Dim [WithEvents] varname[([subscripts])] [As [New] type] [, [WithEvents] varname[([subscripts])] [As [New] type]] . . .
The Dim statement syntax has these parts:
|WithEvents||Optional. Keyword that specifies that varname is an object variable used to respond to events triggered by an ActiveX object. WithEvents is valid only in class modules. You can declare as many individual variables as you like using WithEvents, but you can't create arrays with WithEvents. You can't use New with WithEvents.|
|varname||Required. Name of the variable; follows standard variable naming conventions.|
|subscripts||Optional. Dimensions of an array variable; up to 60 multiple dimensions may be declared. The subscripts argument uses the following syntax:
[lowerTo] upper [, [lowerTo] upper] . . .
When not explicitly stated in lower, the lower bound of an array is controlled by the OptionBase statement. The lower bound is zero if no OptionBase statement is present.
|New||Optional. Keyword that enables implicit creation of an object. If you use New when declaring the object variable, a new instance of the object is created on first reference to it, so you don't have to use the Set statement to assign the object reference. The New keyword can't be used to declare variables of any intrinsic data type, can't be used to declare instances of dependent objects, and cant be used with WithEvents.|
|type||Optional. Data type of the variable; may be Byte, Boolean, Integer, Long, Currency, Single, Double, Decimal(not currently supported), Date, String (for variable-length strings), String * length (for fixed-length strings), Object, Variant, a user-defined type, or an object type. Use a separate Astype clause for each variable you declare.|
Use the Dim statement at module or procedure level to declare the data type of a variable. For example, the following statement declares a variable as an Integer.
Dim NumberOfEmployees As Integer
Also use a Dim statement to declare the object type of a variable. The following declares a variable for a new instance of a worksheet.
Dim X As New Worksheet
If the New keyword is not used when declaring an object variable, the variable that refers to the object must be assigned an existing object using the Set statement before it can be used. Until it is assigned an object, the declared object variable has the special value Nothing, which indicates that it doesn't refer to any particular instance of an object.
You can also use the Dim statement with empty parentheses to declare a dynamic array. After declaring a dynamic array, use the ReDim statement within a procedure to define the number of dimensions and elements in the array. If you try to redeclare a dimension for an array variable whose size was explicitly specified in a Private, Public, or Dim statement, an error occurs.
If you don't specify a data type or object type, and there is no Deftype statement in the module, the variable is Variant by default.
When variables are initialized, a numeric variable is initialized to 0, a variable-length string is initialized to a zero-length string (""), and a fixed-length string is filled with zeros. Variant variables are initialized to Empty. Each element of a user-defined type variable is initialized as if it were a separate variable.
*Note* When you use the Dim statement in a procedure, you generally put the Dim statement at the beginning of the procedure.