The ReDim statement is used to size or resize a dynamic array that has already been formally declared using a Private, Public, or Dim statement with empty parentheses (without dimension subscripts). You can use the ReDim statement repeatedly to change the number of elements and dimensions in an array.
If you use the Preserve keyword, you can resize only the last array dimension, and you can't change the number of dimensions at all. For example, if your array has only one dimension, you can resize that dimension because it is the last and only dimension. However, if your array has two or more dimensions, you can change the size of only the last dimension and still preserve the contents of the array.
The following example shows how you can increase the size of the last dimension of a dynamic array without erasing any existing data contained in the array.
ReDim X(10, 10, 10)
. . .
ReDim Preserve X(10, 10, 15)
|Caution If you make an array smaller than it was originally, data in the eliminated elements is lost.|
When variables are initialized, a numeric variable is initialized to 0 and a string variable is initialized to a zero-length string (""). A variable that refers to an 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