Looping through columns and arrays

[fizban2]

Hi all, new to vb scripting and trying to get work with an excel document and loop through an column on data and add it to an array

Dim i
i = 0
Dim bv
Dim arrBan()
Dim CellValue
bv = 3
'check the length of the column to create an array of good length
Do Until objXL.Cells(bv,15).value = ""
arrBan(i) = objXL.Cells(bv,15).value
i = i + 1
bv = bv + 1
loop

from this i get a subscript out of range error, the column can be any length so i cant set a value to the array but a dynamic array should work fine right?
also to see if my thought proccess is right, overall what i am trying to do is compare 2 excel docs to a third, based on the numbers in this column, what i was going to do was get the get the numbers from the 2 sheets and compare them to the third. long proccess i know but i am slowly working on it any advice would be greatly apprecaited

EDIT: fixed the looping issue the array had to be set to a value, now a better question is there a way to dynamically set a array length based on a number of columns