ReDim Instruction

Syntax:
ReDim [Preserve] name[type][([dim[, ...]])] [As type][, ...]
Group: Declaration
Description:
Redimension a dynamic array. Use Preserve to keep the array values. Otherwise, the array values will all be reset. When using preserve only the last index of the array may change. The number of indexes may not. (A one-dimensional array can't be redimensioned as a two-dimensional array.)
See Also: Dim, Private, Public, Static.
Example:

Sub Main
Dim X()
ReDim X(3)
Debug.Print UBound(X) ' 3
ReDim X(200)
Debug.Print UBound(X) ' 200
End Sub