Question

Could you please explain to me why this simple VBA code fails at the last line (“Subscript out of Range”):

    Dim test() As Variant
    ReDim test(0, 1)
    test(0,0) = "key"
    test(0,1) = 1
    ReDim Preserve test(1, 1)

Answer 1

Resizing with Preserve. If you use Preserve, you can resize only the last dimension of the array, and for every other dimension you must specify the same bound it already has in the existing array.

For example, if your array has only one dimension, you can resize that dimension and still preserve all the contents of the array, because you are changing the last and only dimension. However, if your array has two or more dimensions, you can change the size of only the last dimension if you use Preserve.